How Much Tax Should I Withhold From a 401k Withdrawal?

The right amount of tax to withhold from a 401(k) withdrawal is whatever matches your actual bill: your top marginal federal bracket, plus 10 percentage points if you’re under 59½ and no exception applies, plus your state’s income tax rate. Your plan’s default withholding is a starting point set by law, not an estimate of what you owe. On a lump sum eligible for rollover, that default is a flat 20 percent, and for most people taking a meaningful withdrawal, 20 percent is too low.

What Your Plan Withholds by Default

The default rate depends on the kind of payment you take.

Withholding is a prepayment, not the final tax. Whatever gets sent to the IRS is credited against your actual liability when you file, and you settle the difference.

Why the Default Rarely Covers Your Actual Bill

Your withdrawal stacks on top of every other dollar you earn that year — wages, Social Security, interest, dividends. The combined amount, minus your standard deduction, is what determines your bracket. For tax year 2026, the standard deduction is $16,100 for single filers and $32,200 for married couples filing jointly, and the single-filer brackets run:4Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026

  • 10% up to $12,400
  • 12% from $12,401 to $50,400
  • 22% from $50,401 to $105,700
  • 24% from $105,701 to $201,775
  • 32% from $201,776 to $256,225
  • 35% from $256,226 to $640,600
  • 37% over $640,600

For married couples filing jointly, each bracket is roughly double the single thresholds; the 22 percent bracket, for example, runs from $100,801 to $211,400.4Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026

Then there’s the penalty. If you’re under 59½ when you take the money, the IRS adds a 10 percent tax on top of ordinary income tax, unless a specific exception applies (leaving your job at 55 or later, disability, a qualifying medical expense, a QDRO in divorce, substantially equal periodic payments, or death of the account holder).5Internal Revenue Service. Retirement Topics – Exceptions to Tax on Early Distributions The plan’s 20 percent withholding does not cover this penalty. You report and pay it separately on Form 5329.

A concrete example makes the gap clear. A single filer earning $80,000 in wages takes a $50,000 traditional 401(k) lump sum. Gross income is $130,000; subtract the $16,100 standard deduction and taxable income is $113,900, with the top slice landing in the 24 percent bracket. The plan withholds 20 percent — $10,000 — but the withdrawal itself is taxed largely at 24 percent, and if the filer is under 59½ without an exception, another $5,000 penalty is owed. The $10,000 withheld covers a fraction of the real cost. The rest comes due at filing.

Calculating the Rate You Should Request

Work through four numbers before you request the distribution.

  • Estimate your total income for the year, including the withdrawal, and subtract your standard deduction to get taxable income.
  • Find your top marginal bracket in the 2026 table. That percentage is what each additional dollar of the withdrawal costs in federal income tax.
  • If you’re under 59½ and don’t qualify for an exception, add 10 percentage points for the early withdrawal tax.
  • Add your state’s income tax rate if your state taxes retirement distributions. Some states do, some make withholding voluntary, and a few don’t tax retirement income at all. Your plan administrator withholds based on your state of residence.

The sum is the withholding rate that gets you close to even. For the example above — a filer whose withdrawal sits in the 24 percent bracket, taken before 59½, in a state with roughly a 5 percent income tax — the combined figure is around 39 percent. Requesting 40 percent federal withholding, or 30 percent federal plus separate state withholding, would land much closer than the 20 percent default.

One caution on marginal versus effective rates. Not every dollar of your withdrawal is necessarily taxed at your top bracket; if the withdrawal spans two brackets, part of it is taxed at the lower rate. Using the top marginal rate for the whole withdrawal will slightly over-withhold, which produces a refund rather than a bill. For most people that’s the safer error.

How to Actually Change the Withholding

For a one-time or occasional distribution, you tell the plan what to withhold on Form W-4R. On an eligible rollover distribution — the kind subject to the 20 percent floor — you can request any rate at or above 20 percent, but not below. On a nonperiodic payment that can’t be rolled over, you can request any rate from 0 to 100 percent, and the default without a form is 10 percent.6Internal Revenue Service. 2026 Form W-4R – Withholding Certificate for Nonperiodic Payments and Eligible Rollover Distributions For recurring installment payments, use Form W-4P and enter your filing status and any adjustments.3Internal Revenue Service. About Form W-4P, Withholding Certificate for Periodic Pension or Annuity Payments

Most plan administrators let you enter the election in their online portal when you initiate the distribution. Some still require a signed paper or faxed form. Submit it before the payment is processed; changing it afterward is much harder.

If You Already Under-Withheld

If the money is already out and 20 percent won’t cover what you owe, you can close the gap with quarterly estimated tax payments using Form 1040-ES. The IRS treats income tax as pay-as-you-go, and a large mid-year withdrawal creates uneven income that can trigger an underpayment penalty even if you settle up in April.7Internal Revenue Service. Estimated Taxes

You generally avoid the underpayment penalty if your total payments through withholding and estimated taxes reach at least 90 percent of what you owe for the current year, or 100 percent of the tax shown on last year’s return, whichever is smaller. If your adjusted gross income was over $150,000, the prior-year threshold rises to 110 percent.8Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty If the withdrawal fell in one quarter and skewed your income for the year, the annualized income installment method on Form 2210 can reduce or eliminate the penalty.7Internal Revenue Service. Estimated Taxes

If the Money Is Coming From a Roth 401(k)

The math above assumes a traditional, pre-tax 401(k). A qualified distribution from a Roth 401(k) comes out entirely tax-free, including earnings, so there’s nothing to withhold against. To be qualified, at least five tax years must have passed since your first Roth 401(k) contribution to a plan with that employer, and you must be at least 59½, permanently disabled, or the distribution must be paid after your death.9Internal Revenue Service. Retirement Topics – Designated Roth Account If those aren’t both met, the earnings portion is taxable and can also draw the 10 percent penalty; the contributions themselves come back tax-free because you already paid tax on them.

If You’re Moving the Money to Another Retirement Account

A direct rollover — plan-to-plan or plan-to-IRA, with the check made out to the receiving custodian — has zero withholding. No tax event, no penalty, nothing to calculate. If the check is instead made out to you with the intent of rolling it over within 60 days, the mandatory 20 percent still applies, and you have to replace that withheld 20 percent from another source when you complete the rollover; otherwise the withheld portion is treated as a taxable distribution, and the early withdrawal penalty can attach.10Internal Revenue Service. Rollovers of Retirement Plan and IRA Distributions If a rollover is your goal, request the direct transfer and the withholding question disappears.