Unpacking the New Rules for 401(k) Catch-Up Contributions

Key Concepts

• Catch-up Contributions: Additional elective deferrals allowed for individuals aged 50 and older to boost retirement savings.
• Rothification: The government’s trend of incentivizing or mandating Roth (after-tax) contributions to accelerate current tax revenue collection.
• FICA/Medicare Wages: The specific income metric (Box 3 of W-2) used to determine eligibility for mandatory Roth catch-up contributions.
• Super Catch-up: An additional, higher contribution limit specifically for individuals aged 60–63.
• Tax-Deferred vs. Tax-Free: The distinction between traditional accounts (tax-deductible contributions, taxable withdrawals) and Roth accounts (no deduction, tax-free withdrawals).

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1. Mandatory Roth Catch-up Contributions

Starting in 2026, a significant change affects high-income earners regarding 401(k) catch-up contributions.

• The Rule: If an employee’s wages from their current employer in the prior year exceeded $150,000, any catch-up contributions made in the current year must be directed into a Roth account.
• Income Metric: The $150,000 threshold is based on wages subject to FICA and Medicare taxes (Box 3 of the W-2), not Adjusted Gross Income (AGI).
• Flexibility Impact: This mandate removes the ability to choose a traditional (pre-tax) contribution for the catch-up portion, effectively increasing the employee's current tax burden because they lose the upfront tax deduction.

2. Nuances of Job Changes

The "prior year income" rule creates specific complexities for workers who change employers:

• New Employers: If an individual changes jobs, they have no prior-year income with the new employer. Therefore, they are not subject to the mandatory Roth rule for that specific plan, regardless of their previous salary.
• Mid-Year Changes: An employee might be forced into Roth catch-ups at their former employer, but gain the flexibility to choose traditional catch-ups upon starting at a new company mid-year.

3. The "Super Catch-up" (Ages 60–63)

A specialized provision exists for individuals in the 60–63 age bracket (age at the end of the calendar year).

• Mechanism: This allows for an additional, higher catch-up contribution amount.
• Adjustment: The total catch-up limit for this window is adjusted annually. In 2026, as the standard age-50 catch-up limit increased, the "super catch-up" amount decreased to approximately $3,200 to maintain a consistent total.
• Roth Requirement: Like standard catch-ups, if the $150,000 income threshold is met, these super catch-up contributions must also be made on a Roth basis.

4. Strategic Considerations

Tim Steffen of Baird emphasizes that these decisions should be part of a broader financial plan:

• Liquidity vs. Tax Benefits: While Roth accounts provide tax-free income in retirement, they lack the upfront tax deduction of traditional accounts.
• Control: If an investor prioritizes flexibility and control over their assets, they might opt for a taxable brokerage account instead of a retirement plan, despite the lack of tax-advantaged growth.
• Voluntary Participation: Even if an individual is eligible for catch-up contributions, they are not required to make them. If the Roth mandate does not align with their tax strategy, they may choose to forgo the catch-up entirely.

5. The "Rothification" Trend

The government is actively encouraging Roth contributions to secure immediate tax revenue.

• Government Perspective: By pushing savers toward Roth accounts, the government collects taxes today rather than waiting for future withdrawals.
• Future Outlook: While there is a long-standing fear that the government might eventually tax Roth withdrawals, Steffen argues this is unlikely. Instead, he suggests the government is currently "doubling down" on the Roth model.
• Potential Risks: Steffen notes that while current proposals to cap the total value of Roth accounts have failed, future political shifts could lead to stricter rules or caps on Roth balances to address long-term revenue shortages.

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Conclusion

The landscape for retirement catch-up contributions is becoming increasingly complex, particularly for high earners. The shift toward mandatory Roth contributions for those earning over $150,000 represents a strategic move by the government to capture tax revenue today. Investors should carefully monitor their W-2 Box 3 income, understand how job changes affect their contribution flexibility, and weigh the benefits of tax-free retirement income against the loss of current-year tax deductions.