W-4 After Marriage: Update Withholding in 2026

Marriage is one of the 5 life events the IRS explicitly recommends triggering a W-4 update.

Your filing status changes for the full calendar year of marriage — December 31 weddings mean MFJ rates for all of that year's income. Not updating your W-4 means 9+ months of paychecks withheld at the wrong rate.

Step 1: Filing status change

Check "Married filing jointly" in Step 1(c). This instantly switches your employer to MFJ withholding tables, which have wider brackets and a $32,200 standard deduction (vs $16,100 single). For a $75,000 earner going from Single → MFJ, that's roughly $200/month less federal withholding.

Step 2: Handling two-earner households

The trap with MFJ: if both spouses leave Step 2 blank, both employers assume they're the only source of income, causing under-withholding. Three fixes:

• Option A (best): Use the IRS Tax Withholding Estimator at irs.gov/w4app. It models both incomes and gives each spouse an additional per-paycheck amount for Step 4(c).
• Option B: Both spouses check Step 2(c). This flags that there are 2 earners and adjusts withholding.
• Option C: Use the worksheet in Step 2(b). More manual but mathematically accurate if followed carefully.

Worked example

Scenario: Married June 1, 2026. Spouse A earns $85,000, Spouse B earns $62,000. Combined: $147,000.

Pre-marriage withholding: Each filed as Single. Spouse A withheld ~$13,500/yr federal, Spouse B ~$7,800/yr. Combined: $21,300.

Naive post-marriage W-4: Both switch to MFJ but leave Step 2 blank. Each employer assumes single-income MFJ. Spouse A withholds ~$8,400 (treating $85K as only income), Spouse B withholds ~$3,900. Combined: $12,300 withheld — but actual MFJ tax on $147K is ~$16,100. Balance due at filing: $3,800 + possible underpayment penalty.

Correct W-4 with Step 2: Both check Step 2(c). Employers adjust. Total withholding ~$16,500, close to actual tax. No surprise at filing.

Other considerations

If you file jointly, note Step 3 (dependents) should only appear on ONE spouse's W-4 — never on both. Step 4(b) itemized deductions: use the spouse with higher income. Step 4(c) additional withholding: split between whichever spouse has more bandwidth per paycheck.