What determines whether your refund grows or shrinks

Your refund size depends on how much tax you overpaid during the year, not on the tax code changing. If you earned more money, had different deductions, or changed your withholding, your refund will likely change. The IRS does not decide to give you more or less — you determine it through what you earned, what you claimed, and what your employer withheld from each paycheck.

The most common reason refunds shift year to year is a change in income. A raise, a second job, freelance work, or investment income all increase what you owe. If your employer did not withhold enough to cover the new total, your refund shrinks. The opposite happens if you earned less than last year.

Deductions and credits also move the needle. If you got married, had a child, bought a home, or paid student loan interest, you may have new deductions or credits that lower your tax bill and raise your refund. Losing deductions — such as no longer paying mortgage interest because you paid off the loan — works the other way.

Key Takeaways

  • Your refund size reflects how much tax you overpaid during the year, which changes when your income, deductions, or withholding changes.
  • A raise or new income source usually shrinks your refund unless you also increased your withholding on your W-4 form.
  • New deductions or tax credits — from marriage, children, education, or home ownership — typically increase your refund.
  • You can predict your refund before filing by using the IRS Withholding Calculator or reviewing your pay stubs against last year's return.

How income changes affect your refund

If you earned more this year than last year, your refund will probably be smaller unless you also increased your tax withholding. When you get a raise or take a second job, your employer withholds tax based on the W-4 form you filled out. If that form still reflects your old income level, the withholding will not be enough to cover your new tax bill, and you will owe money instead of getting a refund — or your refund will shrink.

The reverse is true if you earned less. A period of unemployment, a job change mid-year, or reduced hours means less income and usually a larger refund, because you overpaid tax on the smaller total.

Self-employment income and side work complicate the picture. If you freelanced or ran a small business, you may owe self-employment tax in addition to income tax. This tax does not get withheld from a paycheck, so you either owe it when you file or you need to make quarterly estimated tax payments. Either way, your refund shrinks compared to someone with the same gross income from a regular job.

Deductions and credits that change your refund

A tax credit reduces your tax bill dollar for dollar, so a new credit almost always increases your refund. The most common ones are the Child Tax Credit (if you had a baby or adopted), the Earned Income Tax Credit (if you earn below a certain threshold), and education credits like the American Opportunity Credit or Lifetime Learning Credit.

Deductions lower your taxable income, which lowers your tax bill and raises your refund. Standard deductions increased in 2024 compared to 2023, which means most filers will owe less tax this year than last — and get a larger refund, all else being equal. If you itemize deductions instead of taking the standard deduction, changes in mortgage interest, property taxes, charitable donations, or medical expenses will shift your refund up or down.

Marriage and divorce also change your refund. Married filers often pay less total tax than two single filers with the same income, so getting married usually increases your refund. Divorce works the opposite way.

Withholding changes and their impact

Your withholding is the amount your employer pulls from each paycheck and sends to the IRS. If you want a larger refund, you can lower your withholding by changing your W-4 form — but that means less money in your pocket each month. If you want to break even or owe nothing, you can adjust your withholding to match your actual tax bill.

Most people do not change their withholding, so their refund shifts based on income and deductions alone. But if you got a big raise and want to avoid a surprise tax bill, you can file a new W-4 with your employer to increase withholding. The IRS Withholding Calculator (available at irs.gov) walks you through the math.

Life changes like marriage, divorce, or a child also affect the withholding you should claim on your W-4. The form has fields for dependents and filing status, and updating them can prevent a smaller refund or a bill you did not expect.

How to predict your refund before you file

You do not have to wait until you file to know whether your refund will be bigger or smaller. Start by gathering your pay stubs from this year and last year. Compare your gross income — if it is higher, your refund will likely be smaller unless you have new deductions or credits. If it is lower, expect a larger refund.

Next, list any major life changes: marriage, divorce, children, home purchase, education expenses, job loss, or self-employment income. Each one shifts your deductions or credits and changes your tax bill.

The IRS Withholding Calculator lets you enter your income, deductions, and credits to estimate your tax bill and see whether you are withholding enough. If the calculator shows you will owe money, you can adjust your W-4 now to increase withholding for the rest of the year. If it shows a large refund, you can lower your withholding to get more money in each paycheck instead.

When a refund shrinks unexpectedly

A much smaller refund than last year usually means one of three things: you earned more, you lost a deduction or credit, or you lowered your withholding. If none of those happened, check whether you had a major life change you forgot about — a spouse's income, a dependent who aged out of a credit, or investment income you did not report.

If you owed money instead of getting a refund, the same causes apply, but the impact is larger. A significant income increase without a withholding adjustment is the most common culprit. Self-employment income is the second most common, because it carries self-employment tax that does not get withheld automatically.

To avoid this next year, update your W-4 if you expect a major income change, and make quarterly estimated tax payments if you have self-employment income. Both steps keep you from overpaying or underpaying throughout the year.

Frequently Asked Questions

Does the tax code change every year affect my refund?

Tax code changes affect your refund only if they change your deductions, credits, or tax rate. The standard deduction changes annually for inflation, which usually lowers your tax bill slightly. Major code changes — like new credits or deduction limits — affect specific situations, not everyone. Check the IRS website or your tax software to see what changed for your situation.

If I got a raise, will my refund definitely be smaller?

Not necessarily. A raise shrinks your refund only if your withholding did not increase to match. If you filed a new W-4 when you got the raise and increased your withholding, your refund could stay the same or even grow if you also have new deductions or credits. The key is whether you overpaid or underpaid tax during the year.

Can I make my refund bigger by changing my W-4?

Yes, but it costs you money each month. Lowering the number of allowances on your W-4 increases withholding, which means less take-home pay but a larger refund. Most people do this by accident when they do not update their W-4 after a life change. If you want a larger refund on purpose, you are choosing to lend the government money interest-free instead of keeping it in your paycheck.

What if I had a baby this year — will my refund be bigger?

Very likely. A newborn opens the Child Tax Credit, which is worth up to $2,000 per child. This credit directly reduces your tax bill, so it usually increases your refund significantly. You will need the child's Social Security number and birth certificate information when you file.

How do I know if my refund is wrong?

Your refund is correct if it matches your tax bill minus what you paid in withholding and estimated taxes. If you think it is wrong, review your return line by line: check that your income matches your W-2s and 1099s, that your deductions and credits are accurate, and that your withholding is recorded correctly. If you spot an error, you can file an amended return using Form 1040-X.