# 401(k)/403(b) (match/vesting/Roth vs traditional) > Depth-first rabbithole dossier for 401(k)/403(b) (match/vesting/Roth vs traditional); source-anchored research pack. Parent: [Investing and Retirement](https://llms-explorer.com/tree/investing-and-retirement/) · 6 facets · 68 facts · page: https://llms-explorer.com/tree/401-k-403-b-match-vesting-roth-vs-traditional/ ## Structure and components - 16. Employee elective deferrals, Roth or pre-tax, are always 100% vested. https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-vesting 17. Employer contributions in a qualified DC plan may vest at once, on a 3-year cliff (0% for years 1–2, then 100%), or on a 6-year graded schedule (20% after year 2, rising 20% a year to 100% at year 6). https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-vesting 18. All participants must be 100% vested at the plan's normal retirement age and when the plan terminates. https://www.irs.gov/retirement-plans — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#c-vesting` - 7. Section 135(a) of the Revenue Act of 1978 (Public Law 95-600, November 6, 1978, 92 Stat. 2763, 2785) created §401(k). The GAO calls it "the first provision of the Internal Revenue Code to give statutory recognition to 'cash or deferred arrangements.'" https://www.gao.gov/assets/b-214157-o.m..pdf 8. The original §401(k) required a CODA to be part of a qualified profit-sharing or stock bonus plan. It also required employee-elected amounts to be nonforfeitable at all times, which means elective deferrals were 100% vested from the start. https://www.gao.gov/assets/b-214157-o.m..pdf ; https://ww — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#statutory-birth-of-401-k` ## How it works - 38. Under SECURE 2.0 §603, participants whose prior-year FICA wages exceed the Roth catch-up threshold must make all catch-up contributions as Roth. The threshold was $145,000 for 2025 wages and is indexed. https://www.federalregister.gov/documents/2025/09/16/2025-17865/catch-up-contributions 39. Notice 2025-67 raises that threshold to $150,000, so it applies to 2026 catch-ups by employees whose 2025 FICA wages exceeded $150,000. https://www.groom.com/resources/2026-retirement-plan-limits-announced/ 40. Plans must comply with the Roth catch-up rule from 2026-01-01. The final regulations (relea — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#f-secure-2-0-changes-that-alter-roth-vs-traditional-in-practice` - 19. For 2026, a participant whose 2025 FICA wages from the plan sponsor exceeded $150,000 must make catch-up contributions as Roth. The threshold was $145,000 before indexing. https://www.irs.gov/pub/irs-drop/n-25-67.pdf 20. The statutory requirement starts 2026-01-01. The final regulations (published 2025-09-16) generally apply to taxable years beginning after 2026-12-31, with good-faith compliance accepted before then. https://www.truckerhuss.com/newsletter/roth-catchup-regulations/ · https://www.federalregister.gov/documents/2025/09/16/2025-17865/catch-up-contributions 21. Edge case: if a p — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#e-mandatory-roth-catch-up-secure-2-0-603` ## Measurements and reference values - | Pass | Focus | New claims | Total | Rate | |---|---|---|---|---| | 0 | limits, vesting basics, Roth basics | 20 | 20 | 100% | | 1 | SECURE 2.0 (§603, §604, §325, §101), safe-harbor vesting, 403(b) | 14 | 34 | 41% | | 2 | empirical: match take-up, Vanguard 2026, Beshears, Choi, Burman | 10 | 44 | 23% | | 3 | forfeiture litigation, true-up | 4 | 48 | 8% | — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#pass-log-new-information-rate` - 46. **Tax-equivalency invariant:** if the marginal rate is the same at contribution and at withdrawal, pre-tax and Roth give the same after-tax result. The choice depends on whether the rate at withdrawal is lower or higher than the rate today. **[S]** https://www.kitces.com/blog/roth-conversion-analysis-value-calculate-timing-true-marginal-tax-rate-equivalency-principle/ 47. Kitces (2024-09-25) argues for pre-tax during peak earning years: - A pre-tax contribution saves tax at a 35–40% marginal rate. - The same money is often withdrawn, or converted to Roth in low-income years before Social S — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#f-roth-vs-traditional-economic-invariant-and-its-limits` - **[F]** https://www.kitces.com/blog/pre-tax-retirement-contribution-roth-conversion-rmd-social-security/ 48. The same article names the limits of the pre-tax argument: large RMDs, up to 85% taxation of Social Security benefits, and the need for genuinely low-income years. **[F]** https://www.kitces.com/blog/pre-tax-retirement-contribution-roth-conversion-rmd-social-security/ 49. Brown, Cederburg & O'Doherty (J. Financial Economics 126(3), 2017, 689–712) model a progressive tax schedule under uncertainty about future tax rates. They find that most households should hold both pre-tax and Roth ac — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#f-roth-vs-traditional-economic-invariant-and-its-limits` - The curve is declining but has not reached saturation, which needs two consecutive passes under 5%. I estimate 1–2 more passes would still add depth in these areas: - ADP/ACP test arithmetic and HCE definition - the 20% turnover presumption for partial termination - §403(b)(7) and §403(b)(11) withdrawal restrictions - the SECURE 2.0 §101 auto-enrollment mandate for new plans - how the Roth 5-year clock interacts with in-plan conversions — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#pass-curve` - 48. Section 101 of SECURE 2.0 (Code §414A) requires 401(k) and 403(b) plans established on or after 2022-12-29 to auto-enroll participants from 2025 at 3–10% of pay, rising 1 point a year to at least 10% and no more than 15%. Exempt: plans that existed earlier, employers with 10 or fewer employees, businesses under 3 years old, and church and governmental plans. https://www.groom.com/resources/irs-issues-guidance-on-mandatory-automatic-enrollment/ — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#h-default-setting-context-applies-to-new-plans-only` - 28. An employee's own deferrals are always 100% vested. **[F]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-vesting 29. §411(a)(2)(B) sets the slowest vesting schedules a defined-contribution plan may use for employer money: - **3-year cliff:** 100% vested after 3 years of service - **2–6 graded:** 20% after year 2, 40% after year 3, 60% after year 4, 80% after year 5, 100% after year 6 — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#d-vesting` - **[F]** https://www.law.cornell.edu/uscode/text/26/411 30. For vesting, a "year of service" is a 12-month period in which the employee works 1,000 hours (§411(a)(5)). **[F]** https://www.law.cornell.edu/uscode/text/26/411 31. A "break in service" is a 12-month period in which the employee works 500 hours or fewer (§411(a)(6)). **[F]** https://www.law.cornell.edu/uscode/text/26/411 32. Employer money becomes 100% vested at the plan's normal retirement age and on plan termination. **[F]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-vesting 33. Under §411(d)(3 — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#d-vesting` ## Problems, failure modes and limitations - 13. Roth employer contributions (SECURE 2.0 §604) may be designated Roth only if they are fully vested when allocated. The employee must include them in gross income for the year of allocation. They are not wages for income-tax withholding or FICA. The plan reports them on Form 1099-R, code G. https://www.irs.gov/newsroom/secure-2-point-0-act-impacts-how-businesses-complete-forms-w-2 · https://www.mercer.com/insights/law-and-policy/irs-guidance-illuminates-secure-2-0-s-roth-employer-contribution/ 14. Failure mode: the employee owes tax on a Roth match but nothing is withheld, so an under-withh — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#d-roth-vs-traditional-mechanics` - - **C37.** Employee deferrals, pre-tax or Roth, are always 100% vested. This has been true since the 1978 statute required elective amounts to be nonforfeitable. [S4][S40][S51] · M28 P16 H8 - **C38.** §411(a)(2)(B) sets the slowest schedules allowed for employer DC money: a 3-year cliff, or 2–6-year graded (20/40/60/80/100%). [S30][S12][S4] · M29 E1 P17. See X5. - **C39.** A year of service is a 12-month period with 1,000 hours (§411(a)(5)), as the plan document defines it. [S30][S4] · M30 P20 - **C40.** A break in service is a 12-month period with 500 hours or fewer (§411(a)(6)). [S30] · M31 — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#d-vesting` - - **C99.** Cash or deferred arrangements (CODAs) existed before 1978. In the 1950s, mostly banks let employees defer profit-sharing bonuses. [S51] · H1 - **C100.** Rev. Rul. 56-497 (1956) was the first IRS approval of a CODA. [S52] · H2 - **C101.** The IRS reaffirmed CODAs in 1963. The early rulings already required testing of highly paid against non-highly paid employees, a forerunner of the ADP test. [S51] · H3 - **C102.** 1972 proposed regulations would have taxed salary-reduction amounts when made, which was controversial. [S51][S52] · H4 - **C103.** ERISA (1974) grandfathered CODAs that e — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#j-history` - | # | Side A | Side B | Status | |---|---|---|---| | X1 | H33 and the 247wallst article [S96] give the §603 threshold as **$145,000**. P38 says "$145,000 for 2025 wages". | M45, E19 and P39: Notice 2025-67 sets **$150,000 of 2025 wages** for 2026 catch-ups. | $145k is the statutory base; $150k is the 2026 test. P38 contradicts P39 within the practice report. | | X2 | H33 says the final regulations require compliance from 2026-01-01. | E20 and P40 say the statute applies from 2026-01-01 but the regulations generally apply from **2027-01-01**, with good-faith compliance in 2026. M44 matches this — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#contradictions-kept-side-by-side-not-averaged` - 1. Matching contributions must vest at least as fast as a 3-year cliff or a 2-to-6-year graded schedule (20% after 2 years, then +20% a year, 100% after 6 years). Plans may vest faster. https://www.irs.gov/retirement-plans/issue-snapshot-vesting-schedules-for-matching-contributions 2. Full vesting is forced in three cases, whatever the schedule says: normal retirement age, plan termination, and partial termination for affected participants. https://www.irs.gov/retirement-plans/issue-snapshot-vesting-schedules-for-matching-contributions 3. Some plan types have no vesting schedule for the match. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#a-vesting-boundaries` - 21. The Small Business Job Protection Act of 1996 simplified nondiscrimination testing. Starting in the late 1990s, IRS rulings allowed automatic enrollment. https://www.ici.org/system/files/attachments/per12-02.pdf 22. The Taxpayer Relief Act of 1997 (Pub. L. 105-34, August 5, 1997) added §408A, which created the Roth IRA from 1998. This after-tax/tax-free-growth model came before the Roth 401(k). https://www.congress.gov/105/plaws/publ34/PLAW-105publ34.pdf ; https://www.irs.gov/pub/irs-drop/an97-122.pdf 23. EGTRRA (2001) raised the 401(k)/403(b) deferral limit to $11,000 in 2002, then by $1, — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#liberalization-phase-1996-2006` - 36. A designated Roth account is a separate account inside a 401(k) or 403(b). The plan must keep it completely separate from pre-tax deferrals. **[S]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-designated-roth-account 37. Anyone can make designated Roth contributions. No income limit applies. **[F]** https://www.irs.gov/retirement-plans/retirement-plans-faqs-on-designated-roth-accounts 38. A distribution is **qualified**, and so fully tax-free including earnings, only if both conditions hold: - it comes at least 5 taxable years after the first Roth contr — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#e-roth-vs-traditional-account-mechanics` - - **C23.** A 401(k) that is not safe harbor must pass the ADP and ACP tests every year. The tests compare highly compensated employees (HCEs) with everyone else. [S8](S) · M18 - **C24.** The HCEs' average deferral percentage may exceed the non-HCEs' only by the margins set in §401(k)(3)(A)(ii). [S9] · M19 - **C25.** §4979 imposes an excise tax on excess contributions. The employer avoids it by correcting within 2½ months after the plan year ends, or within 6 months for an EACA. [S9] · M20 - **C26.** A match counts in that year's ACP test only if it is deposited within 12 months after the year — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#c-how-the-employer-match-works` - - https://www.gao.gov/assets/b-214157-o.m..pdf — GAO, B-214157-O.M., "Section 401(k) Salary Deferral Plan for GAO Employees," April 2, 1984 - https://www.ici.org/system/files/attachments/per12-02.pdf — ICI Research Perspective Vol. 12 No. 2, "401(k) Plans: A 25-Year Retrospective," November 2006 - https://scholarship.law.wm.edu/cgi/viewcontent.cgi?article=1462&context=tax — William & Mary Tax Conference, "Cash or Deferred Arrangements (Section 401(k))" - https://www.irs.gov/pub/irs-drop/n-07-07.pdf — IRS Notice 2007-7 (PPA §904 vesting) - https://www.everycrsreport.com/reports/RS20629.html — C — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#sources` - 18. In a traditional (non-safe-harbor) 401(k), the employer must run the ADP and ACP tests every year. The tests check that deferrals and matches do not discriminate in favor of highly compensated employees (HCEs). **[S]** https://www.irs.gov/retirement-plans/plan-sponsor/401k-plan-overview 19. Under §401(k)(3)(A)(ii), the HCEs' average deferral percentage (ADP) may exceed the non-HCEs' ADP only by specified margins. **[F]** https://www.irs.gov/pub/irs-drop/n-24-63.pdf 20. Section 4979 imposes an excise tax on excess contributions from a failed ADP or ACP test. The employer avoids the tax by c — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#c-employer-match-mechanism` - **[S]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-designated-roth-account 39. In a nonqualified distribution, the tax-free basis portion is pro-rata: the distribution amount × (Roth contributions ÷ Roth account balance). The earnings portion is taxable. **[F]** https://www.irs.gov/retirement-plans/retirement-plans-faqs-on-designated-roth-accounts 40. If a Roth balance moves by direct rollover from another plan's Roth account, the new plan's 5-year clock starts from the earlier plan's first Roth year. **[F]** https://www.irs.gov/retirement-plans/retirement — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#e-roth-vs-traditional-account-mechanics` - - **C1.** The elective-deferral limit (§402(g)) is $24,500 for 401(k) and 403(b). The same limit applies to governmental 457 plans and the TSP. [S1][S2][S19][S11] · M1 M2 H34 E25 P1 - **C2.** The age-50+ catch-up is $8,000. [S1][S19] · M3 H34 E25 P2 - **C3.** The catch-up for ages 60–63 is $11,250 (SECURE 2.0). It did not change from 2025. [S1][S19] · M4 P3 - **C4.** The §415(c) cap on annual additions is $72,000, up from $70,000. It is $80,000 with the age-50 catch-up and $83,250 at ages 60–63. [S1][S60][S11] · M7 E25 P4 - **C5.** The §402(g) limit applies once per person, across every plan t — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#a-deferral-limits-2026` - - **C11.** Only public schools and colleges, churches, and §501(c)(3) organizations can sponsor a 403(b). [S3][S22] · M10 P45 - **C12.** A 403(b) holds assets in one of three forms: annuity contracts, custodial accounts invested in mutual funds (§403(b)(7)), or church retirement income accounts. [S3] · M11 - **C13.** A 403(b) cannot hold life insurance issued after 2007-09-24. [S3] · M12 - **C14.** Universal availability: if one employee may defer, all employees may. Permitted exclusions include people deferring under $200 a year, nonresident aliens, and people working under 20 hours a week. [ — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#b-403-b-only-rules` - [S6](S) [S20] · M38 P28 - **C58.** A nonqualified distribution is split pro rata between tax-free basis and taxable earnings. The contributions do not come out first. [S5] · M39 E17 - **C59.** Each plan has its own 5-year clock. A direct rollover from another plan's Roth account keeps the earlier start date. [S5] · M40 E15 - **C60.** If Roth plan money moves to a Roth IRA, the years in the plan do not count toward the Roth IRA's clock. The two clocks are independent. [S5] · E16 - **C61.** An in-plan Roth rollover can convert any vested balance, even money the employee cannot yet withdraw. [S5] — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#f-how-the-designated-roth-account-works` - - **Met.** 33 claims drawn from more than 15 independent hosts: irs.gov, federalregister.gov, nber.org / ideas.repec.org, bls.gov, kitces.com, milliman.com, mercer.com, truckerhuss.com, groom.com, hklaw.com, mcdermottlaw.com, uschamber.com, morganlewis.com, thetaxadviser.com, and others. Primary sources (IRS notices and pages, Federal Register, NBER, BLS) back the core rules. - **Disconfirming sources found:** the Beshears et al. Roth study, the BLS wage-offset study, and the forfeiture litigation split. - **Caveats:** 1. The Notice 2024-2 PDF, the Vanguard 2024 match study, and the IRI letter — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#quality-gate` - 1. In 2026, an employee can defer up to $24,500 of salary into a 401(k). **[F]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-401k-and-profit-sharing-plan-contribution-limits 2. The same $24,500 deferral limit applies to 403(b) plans in 2026. **[F]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-403b-contribution-limits 3. The age-50+ catch-up is $8,000 in 2026. **[F]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-401k-and-profit-sharing-plan-contribution-limits 4. Employees aged 60, 61, — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#a-deferral-mechanics-and-limits` - **[F]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-403b-contribution-limits 15. **Ordering rule:** if an employee qualifies for both catch-ups, deferrals above the base limit count first toward the 15-year catch-up and then toward the age-50 catch-up. **[F]** https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-403b-contribution-limits 16. The §401(m) matching-contribution rules apply to 403(b) matches "in the same manner as if the plan were a qualified retirement plan" (§403(b)(12)(A)(i)). **[F]** https://www.irs.gov/pub/irs-dr — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#b-403-b-specific-parts` - 1. For 2026, the elective-deferral limit for 401(k), 403(b), governmental 457 and TSP participants is $24,500. https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500 2. For 2026, the standard age-50+ catch-up for those plans is $8,000. https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500 3. For 2026, the higher catch-up for ages 60–63 (a SECURE 2.0 provision) stays at $11,250. https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500 4. For 2026, the §415(c) annual-addition — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#a-2026-limits-that-constrain-every-decision` - 1. **Is traditional or Roth better for "most" savers?** Burman–Gale–Weiner found that most savers faced lower rates in retirement, which favors traditional (claim 32). The same paper, and the equal-nominal-limit argument, show Roth can win for anyone who maxes out (claim 33). Rule-of-thumb guidance (claim 31) depends on assumptions about future tax law that nobody can verify. This report does not pick a side. 2. **Do matches work?** The match is the standard incentive, but Vanguard (2026) finds that about 59% of match dollars go to workers already saving above the cap. It argues nonelective co — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#unresolved-disagreements` - - **C78.** Tax-equivalency: if the tax rate is the same at contribution and at withdrawal, Roth and pre-tax give the same after-tax result. [S56](S) [S58] · M46 P31 - **C79.** Kitces: this simple equivalency breaks down when tax rates change over time. [S56] · E-disagreement - **C80.** Kitces (2024) favors pre-tax in peak earning years. The contribution saves 35–40% now, and the money is often withdrawn or converted at 10–28%. Pre-tax also keeps the option to convert later. [S55] · M47 - **C81.** The same article names the limits of that argument: large RMDs, up to 85% taxation of Social Secur — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#h-roth-vs-traditional-the-economics` - **Areas where further passes would still add depth:** - ADP/ACP arithmetic and the definition of an HCE - §403(b)(7) and (11) withdrawal restrictions, hardship withdrawals, and in-service withdrawals - Failure modes in plan documents - How the 5-year clock interacts with in-plan conversions - The primary text of Notices 2024-2 and 2025-67, and Publication 571 - The primary rule behind the excess-deferral deadline (X7) - The *Hutchins* Ninth Circuit outcome and 2026 appellate forfeiture rulings. The practice report named Gibson Dunn (February 2026) and NAPA (April 2026) articles but gave no URL — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#saturation-verdict-budget-exhausted-soft-stop` - 28. The 403(b) 15-years-of-service catch-up is available only at qualifying employers (schools, hospitals, health and welfare agencies, churches and church-related organizations). The yearly amount is the least of $3,000, $15,000 minus prior uses (a lifetime cap), or $5,000 × years of service minus prior deferrals. https://www.irs.gov/retirement-plans/403b-plans-catch-up-contributions 29. Ordering rule: the 15-year catch-up is applied **before** the age-50 catch-up. An employee eligible for both can therefore contribute more than a 401(k) participant of the same age. https://www.irs.gov/retire — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#g-403-b-specific-edge-cases` - 13. At the start, 401(k) deferrals were also exempt from FICA. The Social Security Amendments of 1983 made participant contributions subject to employment taxes. https://www.ici.org/system/files/attachments/per12-02.pdf 14. TEFRA (1982) cut the total DC contribution limit to $30,000 for 1983, down from $45,475 in 1982. At first there was no separate limit on employee deferrals. https://www.ici.org/system/files/attachments/per12-02.pdf 15. In 1984, Treasury proposed to repeal §401(k). The proposal was never implemented. https://www.ici.org/system/files/attachments/per12-02.pdf 16. The Tax Refor — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#1980s-restriction-phase` - 11. Per-payroll matching: many plans compute the match each pay period. An employee who reaches the deferral limit early in the year gets no match for the remaining pay periods unless the plan has an annual "true-up". https://thefinancebuff.com/401k-match-every-payroll-true-up.html · https://www.verrill-law.com/blog/401k-plan-matching-contributions-to-true-up-or-not-true-up/ 12. A true-up is a plan-document feature: the plan computes the match on annual compensation. Not every plan has one, so a front-loading strategy depends on the plan's terms. https://www.newfront.com/blog/401kology-annual- — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#c-match-computation-failure-modes` - 29. SBJA 2010 §2112 (Pub. L. 111-240) added §402A(c)(4). It allowed in-plan rollovers of pre-tax balances to a designated Roth account for distributions after September 27, 2010, but only for amounts that were otherwise distributable. https://www.irs.gov/pub/irs-drop/n-13-74.pdf ; https://www.irs.gov/pub/irs-drop/n-10-84.pdf 30. The American Taxpayer Relief Act of 2012 (Pub. L. 112-240, enacted January 2, 2013) extended in-plan Roth rollovers to amounts that are not otherwise distributable. IRS Notice 2013-74 gives the guidance. https://www.irs.gov/pub/irs-drop/n-13-74.pdf ; https://www.congre — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#roth-expansion-2010-present` - 10. Only certain employers can sponsor a 403(b): public schools, colleges and universities, churches, and §501(c)(3) charities. **[F]** https://www.irs.gov/retirement-plans/irc-403b-tax-sheltered-annuity-plans 11. A 403(b) holds assets in one of three wrappers: insurance annuity contracts, custodial accounts invested in mutual funds, or church retirement income accounts. **[F]** https://www.irs.gov/retirement-plans/irc-403b-tax-sheltered-annuity-plans 12. A 403(b) cannot hold life insurance issued after September 24, 2007. **[F]** https://www.irs.gov/retirement-plans/irc-403b-tax-sheltered-ann — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#b-403-b-specific-parts` - 45. Generally only public schools, 501(c)(3) tax-exempt organizations and churches can sponsor 403(b) plans. https://www.irs.gov/retirement-plans/retirement-plans-faqs-regarding-403b-tax-sheltered-annuity-plans 46. Under the universal availability rule, if a 403(b) employer lets one employee defer salary, it must offer deferrals to all employees except those the law allows it to exclude. https://www.irs.gov/retirement-plans/retirement-plans-faqs-regarding-403b-tax-sheltered-annuity-plans 47. A 403(b) participant with 15 or more years at a qualified organization may be able to defer up to $3,00 — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#g-403-b-specific-mechanics` - - https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500 - https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-vesting - https://www.irs.gov/retirement-plans/issue-snapshot-vesting-schedules-for-matching-contributions - https://www.irs.gov/retirement-plans/roth-comparison-chart - https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-required-minimum-distributions-rmds - https://www.irs.gov/retirement-plans/retirement-plans-faqs-regarding-403b-tax-sheltered-annuity-plans - https://www.irs.gov/newsro — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#sources` ## Comparisons and alternatives - - **Concept:** 401(k)/403(b) (match/vesting/Roth vs traditional) - **Parent context:** Investing and Retirement - **Lens:** practice (operational use, trade-offs, evaluation, implications) - **Date:** 2026-09-24 - **Method:** `/rabbithole` depth passes (pass 0 + 3 deepening passes), atomic claims, inline sources - **Verdict:** `BUDGET_EXHAUSTED` (soft stop). New-information rate fell per pass (see the end of this report), but two consecutive passes did not reach the < 5% saturation rule. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md` - IN: how the 401(k) and 403(b) came to exist in law and regulation, plus how three of their features changed over time: the employer match, the vesting of employer money, and designated Roth contributions compared with traditional pre-tax deferrals. The key statutes, IRS/Treasury guidance, and dated milestones are in scope. OUT: IRAs as a product (they appear only where the Roth IRA led to the Roth 401(k)). Also out: 457(b), defined-benefit pensions, SEP/SIMPLE, investment selection, and personal-finance advice. Those are separate frontier items. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#scope` - **In scope:** how employer matches are computed and lost; vesting limits and forced-vesting events; forfeitures; Roth vs traditional deferrals, including Roth employer contributions, the SECURE 2.0 Roth catch-up mandate, 5-year clocks, and RMDs; 403(b)-specific catch-up and investment rules; deferral-limit failures; loan offsets at separation. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#scope` - **In scope:** the internal mechanism of 401(k) and 403(b) employee-deferral plans: - deferral limits and how they aggregate - employer matching, including nondiscrimination testing, safe harbor, true-up, and student-loan match - vesting of employer money - the designated Roth account versus pre-tax deferral, including the SECURE 2.0 changes in force for 2026 — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#scope` - **In scope:** how employer matching contributions, vesting schedules, and the Roth vs pre-tax (traditional) choice work inside 401(k) and 403(b) plans. This covers the 2026 limits that constrain those choices, the evidence on how workers and employers actually use them, and the open disputes. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#scope` - - **Match value.** Calculate the match in dollars at your contribution rate. Contribute at least up to the match cap (claims 9, 14). Check whether the plan matches per paycheck without a true-up before front-loading (claim 15). - **Vesting.** Read the plan's schedule (cliff or graded, years of service) and compare it with how long you expect to stay. Unvested balances are forfeited when you leave (claims 17–19, 23). - **Roth vs traditional.** Compare today's marginal rate with the expected effective rate on withdrawals (claims 31–32). If you max out the limit, give weight to the fact that Roth — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#evaluation-checklist-derived-from-the-claims-above` - - **"Roth is better for young savers" vs the tax-rate factor.** Kitces says current vs future *marginal* tax rate dominates the choice, and that Roth wins on three secondary factors: the tax-exclusive contribution limit when maxing out, no lifetime RMDs, and state estate tax. https://www.kitces.com/blog/roth-vs-traditional-ira-the-four-factors-that-determine-which-is-best/ He also says the simple tax-equivalency result fails when tax rates change over time. https://www.kitces.com/blog/roth-conversion-analysis-value-calculate-timing-true-marginal-tax-rate-equivalency-principle/ Neither source s — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#disagreements-and-disconfirming-evidence-not-resolved` - 1. **Pre-tax vs Roth for high earners (substantive, unresolved).** - Kitces (claim 47) favors pre-tax in peak earning years because of rate arbitrage and the option to convert later. - Brown et al. (claim 49) find that uncertainty about future tax schedules makes Roth valuable even for high earners, and they recommend holding both. - The two positions differ in their assumptions. Kitces treats the future tax schedule as known and the employee's own income path as the variable. Brown et al. treat the tax schedule itself as uncertain. 2. **The IRS FAQ conflicts with the statute on Roth matches ( — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#unresolved-disagreements-and-source-conflicts` - | Pass | Focus | New claims | Total | New-info rate | |---|---|---|---|---| | 0 | IRS topic pages: limits, vesting, 403(b) | 16 | 16 | — | | 1 | Statute §411, Roth FAQ, 403(b) overview | 14 | 30 | 47% | | 2 | SECURE 2.0 §§110/325/603/604, excess deferrals | 12 | 42 | 29% | | 3 | Roth-vs-traditional theory, match timing/true-up, primary check of Notice 2024-63 | 7 | 49 | 14% | — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#pass-curve` - 27. Pre-tax deferrals reduce taxable income now, and withdrawals of contributions and earnings are taxed later. Designated Roth deferrals are made with after-tax dollars, and qualified withdrawals are tax-free. https://www.irs.gov/retirement-plans/roth-comparison-chart 28. A Roth distribution is qualified only if the account has been held at least 5 years and the distribution is made at 59½ or later, on disability, or on death. https://www.irs.gov/retirement-plans/roth-comparison-chart 29. Starting in 2024, designated Roth accounts in a 401(k) or 403(b) have no required minimum distributions d — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#e-roth-vs-traditional-pre-tax-inside-the-plan` - **Scope.** In scope: how deferrals, matching, and vesting work, and designated Roth vs pre-tax deferrals, as of 2026. It also covers 403(b)-only rules, how these features changed over time, and where they fail. Out of scope: IRAs, 457(b), SEP/SIMPLE, pensions, investment choice, and Social Security. Those are handed off at the end. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md` - - **C69.** If an employee's prior-year FICA wages from the plan sponsor exceed the threshold, all their catch-up contributions must be Roth. The rule covers 401(k), 403(b), and governmental 457(b) plans, not SEP or SIMPLE. [S59](S) [S32] · M44 E22 P38 - **C70.** The statutory threshold is $145,000, indexed. Notice 2025-67 set $150,000 of 2025 wages as the test for 2026 catch-ups. [S11][S63][S60] · M45 E19 P39 H33. See X1. - **C71.** The test uses Social Security wages (W-2 Box 3), not Medicare wages (Box 5). Anyone with no FICA wages from the sponsor is exempt at any income. Examples are partn — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#g-mandatory-roth-catch-up-secure-2-0-603` - - **C88.** Beshears, Choi, Laibson & Madrian studied 11 firms that added a Roth option in 2006–2010. Total contribution rates did not change. The authors attribute this to misunderstanding of Roth taxation and to "partition dependence". [S46][S47] · E P35 - **C89.** (inf) Keeping the same nominal rate after switching to Roth means more after-tax saving but less take-home pay now. · P36 - **C90.** At year-end 2024, 86% of Vanguard plans offered Roth and 18% of participants used it, an all-time high. Use is concentrated among higher-income, longer-tenured participants. [S54] · P37 - **C91.** In — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#i-how-people-actually-behave` - - S1 https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-401k-and-profit-sharing-plan-contribution-limits - S2 https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-403b-contribution-limits - S3 https://www.irs.gov/retirement-plans/irc-403b-tax-sheltered-annuity-plans - S4 https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-vesting - S5 https://www.irs.gov/retirement-plans/retirement-plans-faqs-on-designated-roth-accounts - S6 https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-des — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#sources` - - **Met.** The report uses 11 distinct hosts: irs.gov, law.cornell.edu, federalregister.gov, kitces.com, sciencedirect.com, groom.com, verrill-law.com, employeefiduciary.com, currentfederaltaxdevelopments.com, plus the Notice PDFs on irs.gov and a cross-check against the 247wallst.com press article. - Primary sources are the IRC §411 text, Notices 2024-2, 2024-63 and 2025-67, and IRS topic pages. The report includes one peer-reviewed paper and one dated practitioner analysis. - I actively sought a disconfirming source on Roth vs traditional (conflict 1). I also caught two secondary-source erro — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#quality-gate` - - **Congress's intent in 1978.** One account says §401(k) was meant to *limit* executive use of cash-deferred perks (https://en.wikipedia.org/wiki/Revenue_Act_of_1978). ICI says Congress acted because it was "unhappy with the uncertainty surrounding CODAs" and wanted to allow them under conditions (https://www.ici.org/system/files/attachments/per12-02.pdf). Both accounts agree that nobody expected it to become the main retirement vehicle. They disagree on whether its purpose was restrictive or enabling. The Revenue Act's committee reports were not read in this pass. - **"Accident of history" a — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#unresolved-disagreements` - 7. Around 30% of firms in Vanguard's data use a standardized safe-harbor match formula, which exempts the plan from federal nondiscrimination testing. https://corporate.vanguard.com/content/dam/corp/research/pdf/better_match_formulas_401k_plans.pdf 8. Matching contributions are offered in 86% of Vanguard plans, covering 96% of participants. Nonelective (no-contribution-required) employer contributions appear in 46% of plans. https://corporate.vanguard.com/content/dam/corp/research/pdf/better_match_formulas_401k_plans.pdf 9. Take-up of the full match rises with income. In Vanguard's 2023 admini — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#b-employer-match-design-and-how-workers-actually-respond` - 8. Proposed regulations (Feb 2023) say forfeitures must be used within 12 months after the close of the plan year. They may pay plan expenses, reduce employer contributions, or be added to other participants' accounts. A transition rule treats pre-2024 forfeitures as incurred in the first plan year beginning on or after 2024-01-01. https://www.federalregister.gov/documents/2023/02/27/2023-03778/use-of-forfeitures-in-qualified-retirement-plans · https://www.morganlewis.com/blogs/mlbenebits/2023/04/irs-proposes-one-year-limit-on-use-of-forfeitures-in-defined-contribution-plans 9. Litigation: pla — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/edge-cases.md#b-forfeitures-where-unvested-match-goes` - 1. Before 1978, employers could already make before-tax contributions to tax-qualified profit-sharing plans. Some employers, mostly banks, added a "cash or deferred arrangement" (CODA) in the 1950s. It let employees defer a profit-sharing bonus instead of taking it in cash. https://www.ici.org/system/files/attachments/per12-02.pdf 2. The IRS first approved CODAs in 1956 (Rev. Rul. 56-497). The CODA in that ruling was a profit-sharing plan in which each employee elected, before year-end, to take their share of profits as cash or as a plan contribution. https://scholarship.law.wm.edu/cgi/viewcon — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#pre-history-before-401-k` - 35. At year-end 2005, 47 million active participants were in 401(k) plans, compared with 21 million in DB plans. In 1980, there were virtually no 401(k) participants. 401(k) assets passed $1 trillion in 1996 and reached $2.4 trillion in 2005. https://www.ici.org/system/files/attachments/per12-02.pdf 36. At first, 401(k)s were usually supplements to a DB pension at large employers. By 2002, 90% of 401(k) plans were stand-alone plans. https://www.ici.org/system/files/attachments/per12-02.pdf — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#growth-markers` - These concepts came up during the run. They belong to `concept-family-explorer`, not to this report: - governmental 457(b) plans - SEP and SIMPLE IRAs (always 100% vested) - the Roth IRA 5-year rules, which differ from the designated Roth account rules - Roth conversion strategy - RMD rules for pre-tax accounts - taxation of Social Security benefits - EACA and QACA auto-enrollment — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#handoffs-siblings-surfaced-not-chased` - - **Met.** The report uses more than 10 independent hosts: irs.gov, federalregister.gov, nber.org, brookings.edu, corporate.vanguard.com, groom.com, mayerbrown.com, hklaw.com, mercer.com, onedigital.com, capitalgroup.com and cnbc.com. - **Primary sources used:** IRS pages, the Federal Register final rule, NBER papers, and a dated Vanguard research paper. - **Disconfirming sources sought:** yes. Burman–Gale–Weiner (claims 32 vs 33), Vanguard's critique of match formulas, and the forfeiture cases decided on both sides. - **Caveats:** - Claims 4 and 39 cite a law-firm summary of Notice 2025-67, n — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#quality-gate` ## Facts and statements - **[S]** https://www.irs.gov/pub/irs-drop/n-24-02.pdf 44. **Mandatory Roth catch-up (SECURE 2.0 §603):** - If an employee's prior-year FICA wages from the plan sponsor (W-2 box 3) exceed the threshold, all their catch-up contributions must be Roth. - The rule applies to 401(k), 403(b) and governmental 457(b) plans, not to SEP or SIMPLE plans. - Compliance is generally required from 2026-01-01, with good-faith relief through 2026. - A plan may adopt a "deemed Roth" election for affected employees. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#e-roth-vs-traditional-account-mechanics` - MET. The report uses 3 or more independent hosts and primary or official documents: gao.gov (1984 GAO legal memo), irs.gov (Notices 2007-7, 2010-84, 2013-74, 2023-62, and the 2026 limits release), federalregister.gov / govinfo.gov (Roth §402A regulations, 403(b) regulations, RMD and catch-up final rules), congress.gov (Public Laws 105-34 and 112-240), plus secondary sources at ici.org (dated November 2006) and everycrsreport.com (CRS). The disconfirming sources sought were the CODA pre-history and Benna's own account, which counter the "accident" and "inventor" story (see above). Gaps: the JCT — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#quality-gate` - **[S]** https://www.groom.com/resources/irs-issues-final-regulations-on-catch-up-rule-changes/ 45. Notice 2025-67 sets the §603 threshold that decides 2026 Roth catch-ups: FICA wages above **$150,000** in 2025, up from $145,000. **[S]** https://www.irs.gov/pub/irs-drop/n-25-67.pdf and https://www.currentfederaltaxdevelopments.com/blog/2025/11/13/annual-adjustments-to-retirement-plan-limitations-analysis-of-notice-2025-67-for-2026 — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/mechanism.md#e-roth-vs-traditional-account-mechanics` - - governmental 457(b) - SEP and SIMPLE plans - TSP - Roth IRA 5-year rules - Roth conversion strategy - RMDs on pre-tax accounts - taxation of Social Security benefits - EACA/QACA auto-enrollment design - plan loans and QPLO - CITs as a 403(b) investment vehicle - ERISA fiduciary litigation over forfeitures - defined-benefit pensions — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#handoffs-for-concept-family-explorer-not-chased` - - **C56.** The designated Roth account is kept separate from the pre-tax deferrals inside the same plan. [S6](S) · M36 - **C57.** A distribution is qualified, and fully tax-free, only if both conditions hold: - It comes at least 5 taxable years after the first Roth contribution, counting the first year. - It is made at age 59½ or later, on disability, or after death. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/rabbithole-synthesis.md#f-how-the-designated-roth-account-works` - 18. Congress enacted §403(b) in 1958 through §23(a) of the Technical Amendments Act of 1958 (Pub. L. 85-866). It created tax-sheltered annuities for employees of public schools and §501(c)(3) organizations. https://www.federalregister.gov/documents/2004/11/16/04-25237/revised-regulations-concerning-section-403b-tax-sheltered-annuity-contracts 19. From 1958 to 1974, annuity contracts were the only allowed 403(b) investment, so "403(b)" and "tax-sheltered annuity" became synonyms. In 1974 Congress added §403(b)(7), which allowed mutual-fund custodial accounts. https://403bwise.org/education/403b — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/history.md#403-b-track` - The run stopped on budget, not saturation. Likely further depth: primary text of Notice 2025-67 and Notice 2024-2, Pub 571's 15-year catch-up formula and ordering rules, appellate forfeiture decisions from 2026, and in-plan Roth conversions. — source: `~/.global-ai-hub/research-runs/frontier-2026-09-24/401-k-403-b-match-vesting-roth-vs-traditional/reports/practice.md#pass-log-new-information-rate` ## Related concepts - Roth — is a part of 401(k)/403(b) (match/vesting/Roth vs traditional) - 403 — is a part of 401(k)/403(b) (match/vesting/Roth vs traditional) - 401 — is a part of 401(k)/403(b) (match/vesting/Roth vs traditional) - match — is a part of 401(k)/403(b) (match/vesting/Roth vs traditional) - vesting — is a part of 401(k)/403(b) (match/vesting/Roth vs traditional) - traditional — is a part of 401(k)/403(b) (match/vesting/Roth vs traditional)