Guide to SECURE 2.0 Section 603: The 2026 Mandatory Roth Catch-Up Mandate
The SECURE 2.0 Act of 2022 introduced massive structural adjustments to the American retirement system. While many rules are designed to incentivize corporate compliance or provide beneficial savings channels (like the 2026 "Super" catch-up contribution rules for participants aged 60 to 63), other provisions acted as revenue-generating offsets.
Chief among these offsets is Section 603, which targets high-income employees making age-based catch-up contributions to employer-sponsored plans like 401(k), 403(b), and governmental 457(b) plans. Initially scheduled to launch on January 1, 2024, the IRS enacted Notice 2023-62, establishing a two-year administrative transition period that delayed the mandatory start date to January 1, 2026.
1. The Core Threshold & Box 3 Form W-2 Wages
For the 2026 tax year, the mandatory Roth catch-up rule is triggered if a participant's wages from the sponsoring employer in the preceding calendar year (2025) exceeded $150,000. Although the statutory baseline was $145,000, it is adjusted annually for inflation, which the IRS set at $150,000 for 2026.
Crucially, Section 603 specifies that wages are defined by Social Security FICA wages (specifically reported in Box 3 of Form W-2). This creates several important distinctions for payroll departments and executives:
- Single Employer Rule: Wages from previous or unrelated employers are not combined. If a senior executive earns $100,000 at Company A and then transitions mid-year to Company B where they earn another $100,000, they are not subject to the Section 603 Roth mandate at either firm for that tax year because wages did not exceed $150,000 from a single sponsoring employer.
- Sole Proprietors and Partners: Because partners in partnerships and sole proprietors do not receive Form W-2 and do not have FICA wages in Box 3 of a W-2, the IRS has indicated that self-employed individuals are technically exempt from the Section 603 mandate. They may continue to make catch-up contributions on a pre-tax basis even if their self-employment earnings exceed $150,000.
2. The "All-or-Nothing" Employer Plan Risk
One of the most critical elements of Section 603 is the all-or-nothing structural requirement. If a qualified plan allows catch-up contributions, and has even one participant whose prior-year wages exceeded the $150,000 threshold, the plan must offer a designated Roth account option.
If the plan sponsors fail to adopt a Roth option, no catch-up contributions of any kind are permitted for any employee, including those who earn under $150,000 and would otherwise be eligible for pre-tax catch-up options. Plan sponsors and HR managers must urgently audit their 401(k) or 403(b) platforms to ensure that Roth options are active and fully coordinated with their payroll vendors before January 1, 2026.
3. Understanding the 2026 Catch-Up Limit Expansion
Simultaneously in 2026, Section 109 of the SECURE 2.0 Act takes effect, introducing an enhanced "Super" catch-up limit for participants who reach ages 60, 61, 62, or 63 by the end of the calendar year.
| Plan Type | Ages 50–59 & 64+ (Standard) | Ages 60–63 (Super Catch-up) | Section 603 Mandate Scope |
|---|---|---|---|
| 401(k) / 403(b) / 457(b) | $8,000 | $11,250 | Mandatory Roth if wages > $150,000 |
| SIMPLE IRA | $3,500 | $5,250 | Exempt from Section 603 Mandate |
| Traditional / Roth IRA | $1,100 | $1,100 | Exempt from Section 603 Mandate |
4. Financial Optimization: Pre-Tax vs. Roth Opportunity Costs
For participants with wages below $150,000, deciding between Pre-Tax and Roth catch-up contributions involves evaluating current vs. future marginal tax brackets.
For high-earning participants forced into the Roth regime, the decision is made for them, but understanding the financial impact is vital. While they lose the immediate tax deduction (which on a $11,250 super catch-up represents a $3,937 immediate tax cost at a 35% tax rate), they gain access to a powerful compound growth asset.
Because Roth earnings compound completely tax-exempt and are distributed tax-free at retirement, the tax efficiency over a 15-to-20-year horizon frequently outperforms pre-tax contributions. This is especially true when factoring in the capital gains tax drag that would otherwise apply to the taxable reinvestment of immediate pre-tax tax savings. Use our integrated Financial Optimizer above to model your exact tax bracket scenario and projected investment returns.