SIT is a state income tax that New Jersey, New York, and a few other states collect directly from your paycheck

SIT stands for State Income Tax. It is a tax on wages, salary, and other income that your state government collects. Unlike federal income tax, which goes to the IRS, SIT goes to your state's tax department. Most states have one, though a handful do not — New Hampshire and Tennessee, for example, tax only investment income, not wages.

If you live and work in a state with SIT, your employer withholds it from each paycheck, just like federal tax. The amount depends on your state's tax brackets, your income, and the W-4 form you filled out when you were hired. You will see the withholding listed on your pay stub under a label like "State Tax" or "ST" or the state's abbreviation.

At the end of the year, you file a state income tax return — separate from your federal return — to report all your income and settle what you actually owe. If too much was withheld, you get a refund. If too little was withheld, you owe the difference.

Key Takeaways

  • SIT is collected by your state, not the federal government, and the rate and rules vary by state.
  • Your employer withholds SIT from your paycheck based on your W-4 and your state's tax brackets.
  • You must file a state income tax return each year if your income exceeds your state's filing threshold.
  • If you move to a different state mid-year or work in a state where you do not live, you may owe SIT to more than one state.

How SIT withholding works on your paycheck

When you start a job, you complete a W-4 form (or your state's equivalent). This form tells your employer how much federal tax to withhold. Many states use the same W-4 to calculate state withholding, though some states have their own withholding forms.

Your employer uses your filing status, the number of dependents you claim, and your gross pay to calculate the withholding. The calculation follows your state's tax brackets — for example, if you earn $50,000 a year in New York, a portion of that income is taxed at one rate and a portion at a higher rate. Your employer divides your annual withholding by the number of pay periods to determine what comes out each check.

The withholding is an estimate. It assumes you will earn the same amount every pay period for the entire year. If you get a raise, work overtime, or have a second job, the withholding may not be enough. If you take unpaid leave or lose a job partway through the year, too much may be withheld.

Which states have SIT and what the rates are

Forty-one states and Washington, D.C., have a state income tax on wages. Nine states have no income tax at all: Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, Wyoming, and New Hampshire (which taxes only investment income). Three states — Illinois, Mississippi, and Pennsylvania — tax only certain types of income.

State tax rates vary widely. Some states have a flat rate — everyone pays the same percentage regardless of income. Colorado, Illinois, Indiana, Kentucky, Massachusetts, Michigan, North Carolina, and Pennsylvania use flat rates, which range from about 3% to 5.75%. Most other states use progressive brackets, meaning higher earners pay a higher percentage. New York's top rate is 10.9%, California's is 13.3%, and Vermont's is 8.75%. States also differ on what counts as income, what deductions you can take, and whether they tax retirement income.

If you live in a state with no income tax but work in a state that has one, you typically owe SIT to the state where you work. If you work in multiple states, you may owe tax to more than one.

Filing your state income tax return

At the end of the year, you file a state income tax return if your income is above your state's threshold. The threshold varies — some states require a return if you earned any income at all, while others have a minimum (for example, $12,000 for a single filer in some states). Your state's tax department publishes the threshold each year.

You can file your state return on paper or electronically. Many states offer free filing software through the IRS Free File program, which includes state return preparation. Some states have their own free filing portals. If you use a tax professional, they typically file both your federal and state returns together.

On your state return, you report all income from all sources — wages, self-employment, investment income, and other earnings. You claim deductions and credits that your state allows. Common state credits include the Earned Income Tax Credit (EITC), child and dependent care credits, and education credits. Your state return calculates your total tax, subtracts what was already withheld, and shows whether you get a refund or owe more.

What happens if you move during the year

If you move to a different state mid-year, you may owe income tax to both your old state and your new state for the portion of the year you lived in each. This is called part-year resident status. You file a part-year resident return in each state, reporting only the income you earned while you lived there.

Some states offer credits to prevent double taxation. For example, if you paid tax to State A for income you earned there, State B may give you a credit for that tax when you file as a part-year resident. However, not all states offer this credit, and the rules vary. If you move mid-year, check both states' tax websites or consult a tax professional to understand your filing obligations.

If you work in one state but live in another, you typically file as a resident of the state where you live and a nonresident of the state where you work. The nonresident state taxes only the income you earned there. Your home state may tax your worldwide income but often gives you a credit for taxes paid to the other state.

Common mistakes when dealing with SIT

One frequent mistake is not updating your W-4 when your life changes. If you get married, have a child, take a second job, or have a major change in income, your withholding may no longer be accurate. You can adjust it by submitting a new W-4 to your employer at any time during the year.

Another mistake is assuming your federal refund means your state return will also result in a refund. Federal and state withholding are calculated separately, and your federal return does not determine your state return. You may get a federal refund and owe state tax, or vice versa.

A third mistake is missing the state filing important date. Most states follow the federal important date — April 15 — but some have different dates. If you miss the important date and owe tax, you will face penalties and interest. If you cannot file by the important date, you can request an extension, though this extends only the filing important date, not the payment important date.

SIT and self-employment income

If you are self-employed, you owe SIT on your net self-employment income, just as you owe federal income tax. However, SIT withholding does not happen automatically — you do not have an employer to withhold it. You are responsible for setting aside money to pay your state tax bill when you file your return.

Some self-employed people make estimated tax payments to their state throughout the year, similar to federal estimated payments. Your state's tax department publishes the due dates and the amount you should pay based on your expected income. If you do not make estimated payments and owe a large amount at tax time, you may face penalties.

When you file your state return, you report your self-employment income on a schedule (the name varies by state) and calculate your tax. You then compare this to any estimated payments you made and any withholding from other income. The return shows your total tax due or refund.

Frequently Asked Questions

Do I have to file a state return if I did not earn much income?

It depends on your state's filing threshold and your filing status. Some states require a return if you earned any income at all. Others have a minimum threshold — for example, $12,000 for a single filer. Check your state's tax department website for the current threshold. Even if you are not required to file, you may want to if you had taxes withheld, because you could be owed a refund.

What if I worked in two states during the year?

You file a part-year resident return in each state, reporting only the income you earned while you lived or worked there. Some states give you a credit for taxes paid to the other state to avoid double taxation, but not all do. Contact both states' tax departments or consult a tax professional to understand your obligations.

Can I adjust my SIT withholding if I think too much is being taken out?

Yes. You can submit a new W-4 form to your employer at any time to change your withholding. If you expect a large refund, you might reduce your withholding to get more money in each paycheck. If you expect to owe, you might increase it. Use your state's tax withholding calculator (usually available on the state tax department website) to estimate the right amount.

What is the difference between SIT and federal income tax?

Federal income tax goes to the IRS and funds federal programs. SIT goes to your state and funds state programs. They are calculated separately, have different tax brackets and rates, and are reported on different returns. You file both a federal return and a state return (unless you live in a state with no income tax).

Do I owe SIT if I live in a state with no income tax?

If you live in a state with no income tax but work in a state that has one, you owe SIT to the state where you work, not your home state. If you work in a state with no income tax, you do not owe that state's income tax, even if you live in a state that has one.