Idaho Severance Pay Tax Calculator

A lump-sum severance payment is treated as a "supplemental wage" and withheld at a flat 22% federal rate (37% above $1,000,000 in cumulative supplemental wages for the year). Idaho adds its own flat 5.3% state supplemental withholding. Social Security and Medicare taxes also apply to the full amount.

No. Severance formulas (weeks of pay per year of service, notice-period pay, etc.) vary entirely by employer policy, your separation agreement, and in some cases state law — there's no single formula that applies everywhere, so this tool doesn't attempt to calculate it. Enter the lump-sum severance amount from your own agreement, and this calculator estimates only the taxes withheld on that amount.

Generally, no. Most 401(k) plan documents only allow deferrals from compensation for services performed while you're an active employee. Severance paid after your employment officially ends typically doesn't qualify as 401(k)-eligible pay, even though it's still taxed as wages. Check your specific plan document, since rules vary by employer.

Yes. A one-time lump-sum severance payment is withheld at the flat 22%/37% federal supplemental rate. If your severance is instead paid as "salary continuation" (regular paychecks that continue for a period while you're still formally classified as employed), your employer may withhold using your normal W-4-based method instead — which can result in different (higher or lower) withholding than the flat rate this calculator models.

Possibly. Like bonus withholding, the 22% federal rate is a flat minimum, not necessarily your actual tax rate. If your total annual income (including the severance) puts you in a lower bracket than 22%, you'll typically recover the difference as part of your tax refund. If your marginal rate is higher, you may owe additional tax when you file.