GovCon Wednesdays – Estimated Read Time: 6 minutes
When companies process bonuses, PTO payouts, or severance, most of the focus goes to payroll taxes and withholding. But one of the most common—and costly—oversights happens on the benefits side.
401(k) treatment on supplemental wages is not automatic. It depends on your plan document, your payroll setup, and how consistently you apply both. For government contractors, mistakes here don’t just impact employees—they can affect compensation reporting, indirect rates, and audit readiness.
Core Concept: 401(k) Treatment Is Driven by Your Plan Document
There is no universal IRS rule that says supplemental wages must or must not be included in 401(k) calculations. Instead, the IRS requires employers to follow the definition of compensation outlined in their specific 401(k) plan document.
That definition determines whether items like bonuses, commissions, or PTO payouts are:
- Eligible for employee deferrals.
- Included in employer match calculations.
- Counted for annual testing and limits.
If your payroll system processes a bonus differently than your plan document defines compensation, you are out of compliance—even if the payroll tax itself was “technically correct.”
Why This Matters More for GovCons
For government contractors, compensation is not just an HR function—it is a core component of your cost structure.
Under FAR 31.205-6, compensation must be reasonable, allocable, and consistently applied. If your 401(k) contributions are calculated inconsistently across wage types, you may create:
- Misstated Fringe or Overhead Pools: Inaccurate matches can skew your indirect rates.
- Discriminatory Practices: Under FAR 31.205-6(j), pension costs are unallowable if they are discriminatory or inconsistently applied.
- Reconciliation Gaps: Audit questions often arise when there is a mismatch between payroll records, benefit statements, and the general ledger.
Employee Deferrals and 2026 Limits
If your plan allows it, employees may defer 401(k) contributions from supplemental wages. However, payroll teams must be vigilant about the 2026 IRS contribution limits:
- Elective Deferral Limit: $24,500.
- Catch-up Limit (Age 50+): $8,000.
- Super Catch-up (Ages 60-63): $11,250 (per SECURE 2.0).
- The $150k Rule: As of 2026, employees who earned more than $150,000 in 2025 must make catch-up contributions as Roth (after-tax) contributions.
A common issue occurs when payroll systems fail to stop deferrals or fail to redirect catch-ups to Roth accounts for high earners during large mid-year bonus runs.
Employer Match and Supplemental Wages
Whether a bonus or PTO payout is included in the match calculation depends on your plan’s definition of “compensation for matching purposes” and your match frequency (per payroll vs. annual true-up).
If your plan matches “per payroll,” a bonus processed outside the normal cycle might not trigger a match unless the system is specifically configured for it. Conversely, if your plan includes an annual true-up, missing a match during a bonus run may be corrected later—but only if the administration is precise. Coordination with your 401(k) provider is critical to avoid “missed match” liability.
PTO Payouts and Severance Require Extra Attention
PTO payouts and severance are especially tricky. While these are generally supplemental wages for tax purposes, many plan documents specifically exclude severance from 401(k) eligibility once an employee has been terminated.
For GovCons, there is an added layer: how these payments flow through your cost structure. Misalignment between payroll, benefits, and accounting treatment can create inconsistencies in indirect rate calculations that DCAA may flag during an Incurred Cost audit.
Best Practice for Alignment
The most effective way to avoid issues is to ensure your systems and policies are aligned before payments are processed. At a minimum:
- Review the plan document’s definition of compensation annually.
- Confirm payroll system mappings for every wage type (Bonus, Commission, Severance).
- Coordinate with your 401(k) provider before large bonus runs.
- Verify that 2026 “Super Catch-up” and Roth mandates are programmed correctly.
Key Takeaways
401(k) treatment of supplemental wages is driven by your plan document and must be applied consistently to remain allowable under FAR. For government contractors, the risk goes beyond employee impact—it hits your indirect rates and audit readiness.
Resources & Regulatory Guidance
- SECURE 2.0 Act of 2022 – Summary of Provisions – Official U.S. Treasury guidance on 401(k) modernization and mandatory Roth catch-up provisions for high earners.
- IRS Publication 560: Retirement Plans for Small Business – The standard reference for determining eligible compensation and contribution limits.
- FAR 31.205-6: Compensation for Personal Services – The governing regulation for allowability and allocability of pension and compensation costs in government contrac
Ready to Align Your Payroll and Compliance? If your team is processing bonuses or severance without clear alignment between your payroll system and your 401(k) plan, you may be creating unnecessary audit risk.
👉 VSINGH CPA helps government contractors build integrated payroll and accounting processes that support compliance and audit readiness. Let’s review your setup before your next bonus cycle.