Severance payment structure tradeoffs — lump sum vs continuation, 401(k) loans, M&A acceleration

Who this applies to#

One of the first practical questions in any severance negotiation is how the payment is structured — lump sum, salary continuation, installments tied to a specific schedule, or acceleration triggered by a corporate event. Employees often treat this as a secondary concern, but the structure of the payment changes the federal withholding method, the tax year in which income is recognized, the timing of unemployment insurance eligibility, the start of the COBRA election window, and — when a 401(k) loan or equity is involved — exposure to additional penalties and excise taxes. This page consolidates three distinct but related structural scenarios: (1) the fundamental lump-sum vs salary-continuation decision; (2) the 401(k) loan offset that occurs when a plan loan becomes due at separation; and (3) single-trigger vs double-trigger equity acceleration at acquisition or change of control. Each section draws on the primary statutory and regulatory authority governing that scenario and includes actionable planning steps.

What changes for you#

The core choice — lump sum or continuation — has distinct legal and financial consequences that must be modeled before you sign any separation agreement. The three subsections below address the most common structural complications: the lump-sum/continuation choice, the 401(k) loan repayment obligation, and M&A-triggered equity acceleration.

Action steps#

• Before choosing between lump sum and continuation, calculate your expected total W-2 income for the year including severance. If the lump sum would push you into the next tax bracket, model whether salary continuation straddling January would meaningfully reduce the total tax owed.
• If you have an outstanding 401(k) loan, ask your plan administrator whether the balance will be treated as a qualified plan loan offset — if so, you have until the federal income tax return due date including extensions (typically October 15 of the following year) to roll an equivalent amount into an IRA.
• Check your state UI rules. In most states, salary continuation delays UI benefits for the continuation period while a lump sum typically does not. If you will rely on UI immediately, a lump sum is structurally preferable.
• For equity at acquisition, pull every equity award agreement and identify whether each grant is single-trigger or double-trigger. Single-trigger vests automatically at deal close; double-trigger requires both a CIC and a qualifying termination.
• Calculate your § 280G base amount if you are an executive: sum your W-2 Box 1 compensation from the five most recent taxable years before the CIC year and divide by 5. If total contingent CIC payments reach or exceed 3× that base amount, model the 20% § 4999 excise on amounts above 1× base.
• Confirm your agreement's COBRA provisions. If salary continuation maintains group health benefits, coverage loss — and the 60-day COBRA election window — does not begin until continuation ends. A lump sum paid on the last day starts the COBRA clock immediately.
• For continuation packages above $350,000 paid over more than two years, confirm § 409A compliance. Long-duration installment severance carries nonqualified deferred compensation risks.
• Get the structure agreed in writing before your last day. Verbal promises to convert continuation to a lump sum post-separation are difficult to enforce, and § 409A anti-acceleration rules may block conversion anyway.

FAQ#

Is a lump-sum severance always withheld at 22%?

When paid separately from regular wages and identified as a supplemental wage, yes — the mandatory flat rate is 22% under current IRS guidance (IRS Pub 15, 2026). If your cumulative supplemental wages for the calendar year (bonuses, commissions, and severance combined) exceed $1,000,000, the amount above $1 million is withheld at 37%. The withholding does not change your actual tax liability — it is settled when you file — but it affects your upfront cash flow.

Which structure is better for collecting unemployment benefits sooner?

In most states, a lump sum with no period reference does not delay UI benefits; salary continuation delays benefits for each week of continued pay. If immediate UI eligibility matters, a lump sum is generally the better structure outside California. In California, neither lump-sum severance nor salary continuation delays UI benefits under Cal. UIC § 1265. For states with a strong delay rule (Texas, Florida, Washington for tied-to-period payments), negotiating a lump sum can accelerate UI eligibility by months.

When does my COBRA election window start?

Under 26 U.S.C. § 4980B, your COBRA election window starts no later than the date coverage is lost. If your agreement maintains group health benefits during salary continuation, coverage loss — and the COBRA clock — does not begin until the continuation period ends. If the lump sum is paid and health coverage terminates on your last day, the 60-day election window starts immediately. The payment structure can therefore shift your COBRA decision by weeks or months.

What is a plan loan offset and why does it matter at layoff?

A plan loan offset occurs when your 401(k) plan reduces your vested account balance by the amount of your outstanding loan, typically because you separated from employment and cannot repay in cash. Under 26 U.S.C. § 72(p)(1), the offset amount is treated as a distribution — meaning it is includible in your gross income and, if you are under 59½, subject to the 10% early-withdrawal penalty under § 72(t).

How long do I have to roll over a plan loan offset to avoid the tax hit?

Under current law (26 U.S.C. § 402(c)(3)(C), added by TCJA 2017), you have until the due date, including extensions, for filing your federal income tax return for the year in which the offset occurred. For most taxpayers who file for extension, that is October 15 of the following year. To avoid tax, you contribute an equivalent amount to an IRA or another eligible retirement plan by that deadline. The CARES Act 2020 one-year deferral is expired and has no effect on 2026 separations.

What if my employer files for bankruptcy during my salary continuation period?

Unpaid salary continuation installments become an unsecured claim against the bankruptcy estate. Unsecured wage creditors have a priority claim under the Bankruptcy Code up to $17,150 (effective April 1, 2025 per 11 U.S.C. § 104) for wages earned within 180 days before filing, but amounts above that threshold are treated as general unsecured claims — which often receive pennies on the dollar. A lump sum paid before a bankruptcy filing eliminates this risk entirely.

What is the difference between single-trigger and double-trigger equity acceleration at acquisition?

Single-trigger equity vests automatically when a qualifying change of control closes, regardless of whether you are retained. Double-trigger requires both a qualifying CIC and a qualifying termination (typically involuntary layoff or constructive dismissal) within a defined window — usually 12 to 24 months after close. Single-trigger is better for the employee (certain vesting) but is now rare in new grants at public companies and opposed by ISS and Glass Lewis. Double-trigger is the market standard and creates risk that the acquirer retains you in a reduced role without triggering acceleration.

What is the § 280G excise tax and when does it apply at acquisition?

IRC § 280G is triggered when total contingent CIC payments — severance cash, accelerated equity, benefits, retention bonuses — reach or exceed 3× your 5-year average W-2 base compensation. Once triggered, the 20% excise tax under § 4999 applies to every dollar above 1× the base amount, not just to dollars above 3×. For example: if your base amount is $200,000 and total CIC payments are $700,000, the trigger is met (3× = $600,000) and the excise applies to $500,000 of "excess parachute payments," generating a $100,000 non-deductible excise obligation stacked on top of ordinary income tax.

Can I negotiate to convert continuation to a lump sum after separation?

Acceleration of deferred compensation is restricted by § 409A if the plan is subject to that section. Converting a § 409A-covered continuation to a lump sum would violate the anti-acceleration rule and trigger immediate income inclusion plus the 20% additional tax. For continuation arrangements that fall within the § 409A separation pay exception or short-term deferral safe harbor, a post-separation conversion may be possible if both parties agree in writing — but it requires careful drafting and should be reviewed by a tax advisor.

Sources#