Your W-4 isn't set-and-forget. It's built around your filing status, your dependents, and your household's income. When any of those change, the amount withheld from your paycheck stops matching what you'll actually owe — and you find out the hard way at tax time.
A few minutes updating the form after a big life event keeps your withholding honest. Here's what should trigger a change and why.
You got married
Marriage changes your filing status, which changes your tax brackets and standard deduction. If you keep your W-4 on Single, your withholding is calculated with the wrong numbers.
Two things to update:
- Filing status in Step 1 — switch to Married filing jointly (or Married filing separately if that's your plan).
- Step 2's multiple-jobs box if your spouse also works. Two incomes in one household are the number-one reason married couples owe at tax time. Each job withholds as if it's the only paycheck, so not enough comes out combined. Check the box on the higher-paying job's W-4.
You had or adopted a child
A new child usually means a new dependent credit — and money you don't have to wait until April to see.
In Step 3, add the credit: qualifying children under 17 are worth $2,000 each. Enter the total dollar amount for all your dependents (add $500 for each other dependent who isn't a qualifying child). This lowers the tax withheld from every paycheck, spreading the credit across the year instead of holding it back until you file.
You (or your spouse) picked up or dropped a job
Any change in the number of paychecks in your household changes the math.
- Added a second job or your spouse started working? Check the Step 2 box on the higher earner's W-4, or you'll under-withhold and owe.
- Dropped a job or a spouse stopped working? Uncheck it, or you'll over-withhold and hand the IRS an interest-free loan.
Your income changed a lot
A big raise, a bonus that repeats, a spouse's income jumping — these can push your household into a higher bracket than your current W-4 assumes. If you're worried about coming up short, the cleanest fix is Step 4(c), extra withholding: a flat dollar amount taken out of each check on top of everything else. Side income that has no withholding at all (freelance, interest, dividends) can go in Step 4(a) so tax on it comes out of your regular paycheck.
Make the change when the event happens
Don't wait for January. Update the W-4 in your Employee Portal within a pay period or two of the event, so the corrected withholding runs across as much of the year as possible. The editor and exact steps are in Profile & W-4. Changes apply to your next paycheck going forward — they don't fix checks that already ran.
If you're not sure what your new numbers should be, the IRS Tax Withholding Estimator (linked on the W-4 page) takes your household details and tells you exactly what to enter.
Related: How to fill out your W-4 · Adjust your tax withholding · Profile & W-4.