Switching to married filing jointly on your W-4 typically increases your take-home pay, because your employer starts withholding federal income tax against the larger joint standard deduction and the wider joint tax brackets. How much your paycheck actually changes depends on whether your spouse also works, how your incomes compare, and whether you update the form correctly. Skip the two-earner section of the W-4 and the raise you see now can turn into a bill in April.
Why the Paycheck Changes
Two things drive the difference. The first is the standard deduction, which is the slice of income the government doesn’t tax at all. For 2026, a single filer’s standard deduction is $16,100; a couple filing jointly gets $32,200, exactly double.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Federal law sets the joint amount at 200% of the single amount.2Office of the Law Revision Counsel. 26 USC 63 – Taxable Income Defined Once your payroll system knows you’re filing jointly, it treats an additional $16,100 of your income as untaxed and calculates withholding on a smaller base.
The second is the bracket structure. Federal income tax is progressive, with rates climbing as income rises.3Office of the Law Revision Counsel. 26 USC 1 – Tax Imposed Through the 32% rate, the joint-filer thresholds are exactly twice the single-filer thresholds. The 10% bracket covers the first $12,400 for a single person and the first $24,800 for a couple; the 12% bracket runs to $100,800 jointly.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 The lower earner benefits most: income taxed at 22% or 24% on a single return can drop into a lower bracket once it sits on a joint one.
Filing a New W-4 With Your Employer
Your employer keeps withholding at your prior status until you tell them otherwise. The tool for that is IRS Form W-4, the Employee’s Withholding Certificate.4Internal Revenue Service. About Form W-4, Employee’s Withholding Certificate The IRS says newly married employees should submit an updated W-4 within 10 days of the change.5Internal Revenue Service. Tax Checklist for Newlyweds
The setting that actually moves your paycheck is Step 1(c). Checking the “Married filing jointly” box tells payroll to apply the joint standard deduction and joint brackets.6Internal Revenue Service. Form W-4, Employee’s Withholding Certificate Download the current version from irs.gov, or submit through your employer’s HR portal. Expect one or two pay cycles before the new withholding shows up. When it does, compare the federal income tax line on your new stub to an older one; if nothing changed, or the numbers look off, contact payroll before another cycle runs.
The Two-Earner Problem
Most payroll systems assume each employee is the only earner in the household. If both spouses check “Married filing jointly” and leave it there, both employers apply the full $32,200 standard deduction and the wide joint brackets to that single paycheck. Neither employer is withholding enough, and the shortfall is not small. This is the single most common reason newly married dual-income couples owe at tax time.
Step 2 of the W-4 exists to fix it. You have two options: check the box in Step 2(c) for a simplified calculation, or run the Multiple Jobs Worksheet and put the resulting dollar figure on Step 4(c) of the higher-earning spouse’s W-4.6Internal Revenue Service. Form W-4, Employee’s Withholding Certificate That extra amount is pulled from each check to close the gap. Coordinate between both W-4s, but load the extra withholding on only one.
The IRS Tax Withholding Estimator at irs.gov usually beats the paper worksheet for two-income couples, because it accounts for both salaries, credits, and deductions in one pass and produces a pre-filled W-4.7Internal Revenue Service. Tax Withholding Estimator Run it after the wedding and again after any raise, bonus, or job change.
Claiming Credits and Deductions on the W-4
Step 3 lets you reduce withholding for expected credits, including the Child Tax Credit. For joint filers, the credit’s phaseout doesn’t start until household income passes $400,000, so most married couples with kids can claim the full amount here.6Internal Revenue Service. Form W-4, Employee’s Withholding Certificate
Step 4(b) reduces withholding further if you expect to itemize deductions above the standard deduction, or claim above-the-line items like student loan interest. The W-4’s Deductions Worksheet walks through the common categories. Be honest with the numbers. Overstating deductions here means a fatter paycheck now and a bill in April.
What Doesn’t Change
Filing status has no effect on Social Security or Medicare withholding. Both are flat-rate: 6.2% for Social Security up to the annual wage cap, and 1.45% for Medicare on every dollar. Compare pre- and post-marriage stubs and those two lines should be identical. Only the federal income tax line moves.
State income tax is a separate form. A few states accept the federal W-4; most require their own. If you’re in one of the nine states with no income tax, this step doesn’t apply. Everyone else should check with payroll or the state tax agency to update state withholding at the same time.
Where High Earners Get a Smaller Break
The doubling of brackets stops above 32%. A single filer reaches the 37% top rate at $640,600 of income; a joint couple hits it at $768,700, not the $1,281,200 that a true doubling would give.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Two spouses each earning $500,000 would stay at 35% as singles but push part of their combined income to 37% jointly. This is the familiar marriage penalty, and it hits couples with high, similar incomes.
The Additional Medicare Tax has its own gap. Employers withhold an extra 0.9% on wages above $200,000 per employee regardless of filing status, but the joint liability threshold is $250,000, not $400,000.8Internal Revenue Service. Questions and Answers for the Additional Medicare Tax If both spouses earn $150,000, neither employer withholds the surtax during the year, but the couple owes it on $50,000 of combined wages at filing.
The Underpayment Penalty in Year One
If you owe more than $1,000 when you file and didn’t meet a safe harbor during the year, the IRS charges an underpayment penalty.9Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty The rate has recently been 7%, applied quarterly to the amount underpaid.10Internal Revenue Service. Quarterly Interest Rates
You’re safe if your withholding and estimated payments cover the smaller of 90% of the current year’s tax or 100% of last year’s. Couples with adjusted gross income above $150,000 need 110% of last year’s tax instead.9Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty The first year of joint filing is the trickiest, because there’s no prior joint return to benchmark against. Run the withholding estimator soon after the wedding, run it again in the fall, and adjust Step 4(c) if the projection shows a shortfall. Two check-ins beat one April surprise.