Start with your state's tax calculator or worksheet
Most states publish a free tax refund calculator on their department of revenue website. You enter your filing status, income, deductions, and tax withholding for the year, and the calculator shows you an estimated refund or amount owed. The calculator uses the same tax tables and rules the state uses to process your actual return, so the estimate is usually within a few hundred dollars of what you'll actually receive.
If your state does not have an online calculator, you can download the state tax form and instructions for the year you're estimating. The instructions include a worksheet that walks you through the calculation step by step. This takes longer than a calculator but gives you the same result.
You can find your state's calculator by searching "[your state] tax refund calculator" or by going to your state's department of revenue website directly. Most states list it under "Tools" or "Tax Resources" near the top of the page.
Key Takeaways
- Your state's tax calculator or the worksheet in the tax form instructions will estimate your refund within a few hundred dollars of the actual amount.
- You need your W-2 forms, 1099 forms, and the total state tax withheld from your paychecks during the year to run an estimate.
- If you made major life changes during the year — marriage, a new job, a second income — your estimate will be more accurate if you account for those in the calculator.
- An estimate made early in the year may change if your income or withholding changes before you file, so re-run the calculator closer to your filing deadline if your situation shifted.
Gather your income and withholding documents
Before you use the calculator, collect the documents that show your income and how much tax was withheld. For W-2 income, you need your W-2 forms from each employer. For self-employment income, you need records of what you earned. For investment income, 1099 forms from your bank or brokerage. For any other income — unemployment, Social Security, retirement distributions — you need the 1099 form for that income type.
You also need to know the total state income tax withheld from your paychecks during the year. This appears on your W-2 forms in Box 5 (state income tax withheld). If you had multiple jobs, add up the state tax withheld from each W-2. If you made estimated tax payments to the state, include those as well.
Once you have these numbers, the calculator will ask you to enter them. The calculator then subtracts your withholding and payments from your tax liability to show whether you'll get a refund or owe money.
Account for deductions and credits specific to your state
State tax calculations differ from federal calculations because states offer different deductions and credits. Some states let you deduct property taxes or charitable donations. Others offer credits for child care, education, or low-income households. A few states have no income tax at all.
The state tax calculator will prompt you for the deductions and credits you're may have access to to claim. If you're not sure whether you may have access to for a particular credit, the calculator usually includes a brief description or a link to more information. Read these carefully, because missing a credit you may have access to for will make your estimate too high.
If you claimed deductions or credits on last year's return, you can use those as a starting point. But if your situation changed — you bought a house, had a child, paid for education, or your income dropped — you may now may have access to for different credits or deductions than you did last year.
Understand why your estimate might differ from your actual refund
An estimate is not a may provide. Several things can cause your actual refund to differ from what the calculator shows. If you made a mistake entering your income or withholding, the estimate will be off. If you received income late in the year that you did not account for, or if you made a large charitable donation you forgot to include, the estimate will change.
Changes to your life during the year also shift the estimate. If you got married, had a child, bought a house, or started a new job partway through the year, your actual tax situation may be different from what you estimated at the beginning of the year. Re-running the calculator with updated information will give you a more accurate picture.
Some states also adjust refunds if you owe money to the state for other reasons — unpaid child support, student loan debt, or outstanding taxes from a previous year. The calculator cannot account for these offsets, so your actual refund may be smaller than the estimate.
Use your federal estimate to cross-check your state estimate
If you are also estimating your federal refund, you can use that as a sanity check on your state estimate. Your federal and state tax situations are usually related — if your federal refund is large, your state refund is often large too, though not always by the same amount. If your federal estimate shows a small refund but your state estimate shows a large one, go back and check that you entered the same income and withholding numbers into both calculators.
States tax income differently than the federal government does. Some states do not tax retirement income, others do not tax Social Security, and a few do not tax capital gains. So it is normal for your state refund to be different from your federal refund. But the total income you enter should be the same in both calculators.
Recalculate closer to your filing deadline if your situation changed
If you ran an estimate early in the year, consider running it again a few weeks before you file. If your income, withholding, or personal situation changed between when you first estimated and now, the new calculation will be more accurate. This is especially important if you had a major life event — a job change, a second income, a marriage, or a child born late in the year.
You can run the calculator as many times as you want. Each time you run it, use the most current information you have. The final estimate you run just before filing will be the closest to your actual refund.
Know the limits of an estimate
A state tax calculator estimates your refund based on the information you enter and the tax rules in effect when you run it. It does not account for errors you might make on your actual return, and it does not know about offsets or other adjustments the state might apply after you file. If you have a complex tax situation — you own a business, you have rental income, you live in one state but work in another — the calculator may not be accurate enough for your needs. In that case, talking to a tax professional who knows your state's rules can give you a better estimate.
Also, state tax laws change from year to year. A calculator built for the current tax year will not work for next year's taxes. When you file next year, use the calculator for that year.
Frequently Asked Questions
Can I estimate my refund without my W-2 forms?
You can make a rough estimate using your pay stubs from throughout the year, which show your gross income and state tax withheld. But your W-2 forms are more reliable because they show your final annual income and withholding. Wait for your W-2 forms to arrive before you run a final estimate.
What if I owe money instead of getting a refund?
The calculator will show you that you owe money if your tax liability is higher than your withholding and payments. You can then decide whether to file early and pay, or to wait and file closer to the deadline. Some states allow you to set up a payment plan if you owe a large amount.
Does the calculator account for state tax offsets?
No. If you owe child support, student loans, or back taxes, the state may reduce your refund to pay those debts. The calculator cannot predict this. Your actual refund may be smaller than the estimate if an offset applies to you.
How accurate is a state tax calculator?
For most people with straightforward income and withholding, the estimate is usually within a few hundred dollars of the actual refund. The more complex your tax situation — business income, rental property, multiple states — the less accurate the estimate becomes.
Should I adjust my withholding based on my estimate?
If your estimate shows you will get a large refund every year, you could adjust your W-4 form with your employer to reduce withholding and get more money in each paycheck instead. If the estimate shows you will owe money, you could increase withholding. Talk to your employer's payroll department about making changes.