What Is a State Tax Return and How Do You File One?
Navigate the state tax return process by understanding your filing obligations based on residency and how your federal return informs your state tax liability.
A state tax return is a document used to report income and calculate tax obligations to a state government, similar to the federal return filed with the IRS. The purpose is to determine the amount of state income tax you owe or the refund you will receive. Revenue from these taxes funds public services like state highways, schools, and law enforcement. Each state has its own tax laws, forms, and filing requirements, so the process can differ significantly depending on where you file.
Determining Your State Filing Requirement
Your obligation to file a state tax return depends on your residency status and income level. States categorize taxpayers into three residency statuses with different filing rules. A full-year resident is domiciled in a single state for the entire tax year and must report all income from any source to that one state.
A part-year resident is an individual who moved from one state to another during the tax year. For example, if you relocated for a new job in July, you would be a part-year resident of both your old and new states. You would file a return in both states, reporting the income you earned while living in each one.
A nonresident lives in one state but earns income from another, such as commuting to a job in a neighboring state. This individual files a resident return in their home state reporting all income, and a nonresident return in the work state reporting only the income earned there. To prevent double taxation, most states offer a tax credit for taxes paid to another state.
Beyond residency, each state sets income thresholds that determine who must file. These thresholds vary based on filing status, age, and dependents. Several states do not have a personal income tax. As of 2025, the states without a general income tax are:
- Alaska
- Florida
- Nevada
- New Hampshire
- South Dakota
- Tennessee
- Texas
- Washington
- Wyoming
New Hampshire eliminated its tax on interest and dividend income in 2025. Washington does not have a general income tax but does tax certain high-value capital gains.
Information and Forms Needed to Prepare Your Return
The starting point for most state income tax returns is a figure from your federal return, the Federal Adjusted Gross Income (AGI). This means you need to complete, or at least draft, your federal return before preparing your state return. You will need documents like Forms W-2 from employers and any 1099 forms reporting other income.
After finding your federal AGI, you must make any state-specific adjustments. States require certain additions to or subtractions from your federal AGI to calculate your state taxable income. An example of an addition is interest from municipal bonds issued by other states, which is taxable by your home state even if it is tax-free federally. A common subtraction is for Social Security benefits, which many states do not tax.
States also offer their own deductions and credits that are separate from federal ones. These can cover expenses ranging from contributions to a state-sponsored 529 college savings plan to credits for renewable energy installations. You must consult your state’s tax instructions to identify all the deductions and credits you are eligible for.
The official forms and instructions for your state can be found on the website of its Department of Revenue or equivalent tax agency. These websites are the source for the main income tax form and any supporting schedules for adjustments, deductions, and credits.
The Filing Process
The two primary methods for filing your completed return are electronically (e-filing) and by mail. E-filing is done through tax preparation software or a free portal on your state’s tax agency website. This method is faster, results in fewer errors, and provides confirmation of receipt. Filing by mail involves printing, signing, and sending the completed tax forms to the address specified in the instructions.
The deadline for filing your state return and paying any tax owed is the same as the federal deadline, April 15th. If you cannot file by this date, you can request an extension. An extension provides more time to file the return, but not more time to pay the tax you owe. In many states, a federal extension automatically grants a state extension, but some states require a separate form.
You must submit payment by the April 15th deadline to avoid penalties and interest if your return shows you owe taxes. Payments can be made electronically on the state’s website, or by mailing a check with a payment voucher. If you are due a refund, e-filing with direct deposit is the fastest way to receive it. Most state tax agency websites have a tool to track your refund’s status.