When to Change Your W-4 After a Raise or Job Change

Consider changing your W-4 whenever your income or household changes in a way that shifts your tax bill: a second job, a spouse starting or leaving work, marriage or divorce, a new child, or meaningful side income. You can give your employer a new Form W-4 at any time, and it usually takes effect within a pay period or two. The goal is for withholding to match your expected tax, so you avoid both a large refund and a surprise bill. This article covers federal withholding in general terms.

A W-4 does not change what you owe. It changes how much is taken from each paycheck on the way. Your actual tax is settled when you file.

What the W-4 does

Your employer uses the form to decide how much federal income tax to withhold. Withholding is an estimate of your annual tax spread across your pay periods, based on your pay and the information on the form. That estimate assumes the paycheck is your only income unless you say otherwise, so any change in your circumstances can make it inaccurate.

Tax withheld is credited toward your final bill. If too much was withheld, you get a refund. If too little, you owe the difference, and in some cases an underpayment penalty.

Events that usually call for a new W-4

The IRS Tax Withholding Estimator page lists new employment, income changes, marriage or divorce, and the birth or adoption of a child as times to recheck. In practice these are the common triggers:

1. A raise or a new job. Withholding generally adjusts with pay, but a mid-year job change makes a mismatch more likely.
2. A second job. Each employer withholds as if that job were your only one, which tends to under-withhold because the combined income is taxed at higher marginal rates.
3. A spouse starting, stopping or changing work. Two-earner households face the same issue as someone with two jobs.
4. Marriage or divorce. Filing status changes brackets and the standard deduction, so withholding should change too.
5. A new child or dependent. Credits for dependents can be reflected in Step 3.
6. Significant side income. Self-employment income has no withholding, and extra withholding from your job is one way to cover it.
7. A large change in deductions. If you itemize and your total exceeds the standard deduction, Step 4(b) can lower withholding.
8. Income lost mid-year. A stretch of unemployment or reduced hours can lead to over-withholding afterward.
9. A big refund or a surprise bill last year. Either is a sign the form needs attention.

How big a change matters

Not every change needs action. Many people review the form when expected household income shifts noticeably or the household structure changes. Smaller raises usually flow through without trouble. The IRS also recommends checking withholding every January.

The reason to act early is arithmetic. Suppose you find a shortfall of a few hundred dollars in January. Spread over eleven or twelve months, the fix is small per paycheck. Found in September, the same shortfall must be recovered from only a few remaining paychecks, so each one drops far more. Tax withheld from pay is generally treated as paid evenly across the year, which can soften a penalty even when the fix is late.

What to change on each part of the form

• Step 1: personal details and filing status.
• Step 2: multiple jobs or a working spouse. Use the Estimator, the form’s worksheet, or the checkbox when there are exactly two jobs with similar pay. Complete this step on only one job’s form, usually the higher-paying one.
• Step 3: dependents and credits. Enter the dollar amount of credits you expect to claim.
• Step 4(a): other income not from jobs, such as interest or side income, which increases withholding.
• Step 4(b): deductions beyond the standard deduction, which decreases withholding.
• Step 4©: an extra flat dollar amount to withhold each pay period.
• Step 5: sign and date.

The IRS Tax Withholding Estimator uses recent pay stubs, and last year’s return if you have other income, and it can generate a W-4 for you. The IRS says it takes about 25 minutes.

Comparing ways to cover a gap

Choosing between withholding and payments for side income is covered in how to file taxes with side income and a regular job and how quarterly estimated taxes work.

New job, seasonal work and mid-year starts

Starting a job in the middle of the year raises its own questions. Your new employer begins withholding as though you will earn that pay for a full year, so the result can be too high or too low depending on what you earned earlier and what happens next. Seasonal workers and people with a gap between jobs face the same mismatch in reverse. If you start a second job partway through the year, treat the combined income carefully: the Estimator asks for pay information from every job so it can suggest an entry that reflects the total. Whenever a pay change makes you unsure, rerun it rather than guessing.

How to submit the change

1. Gather recent pay stubs and last year’s return.
2. Use the Tax Withholding Estimator to find your target.
3. Fill out a new Form W-4, or use your employer’s online system.
4. Give it to payroll or human resources.
5. Check your next paycheck or two to confirm the change.
6. Review again in a few months, especially midyear.

You do not file the W-4 with the IRS. It stays with your employer.

After a refund versus after an income change

After a big refund you usually want to lower withholding, as described in how to adjust your withholding after a big refund. After a raise, a second job or other income gain, you may need to raise it. The same form and the same estimator handle both directions.

Traps

• Too little withholding. You may owe a balance and possibly an underpayment penalty. The safe-harbor figures are in Publication 505, so check the current percentages there.
• Too much withholding. You are lending money to the government interest-free.
• Bonuses and supplemental pay. These are often withheld at a flat percentage, which can be higher or lower than your real rate. Your final tax still depends on total income.
• Forgetting state withholding. Most states with an income tax have their own form, and a federal change does not update it.
• Updating once. A form that was right in January can be wrong by fall.
• Trusting the estimator blindly. It depends on what you enter, and future income is still a guess.

If your situation is complicated, for example several jobs, self-employment and a spouse’s changing income, a tax professional or a free Volunteer Income Tax Assistance site can help you choose entries.

Where this comes from

This article is based on the IRS Tax Withholding Estimator page and the IRS pages on estimated taxes, along with the layout of the current Form W-4. Withholding rules, safe-harbor percentages and thresholds change, so check the current figure at irs.gov (IRS) or in the form instructions.