Box 15 on a W-2 identifies the state where your employer withheld income tax and shows that employer’s state-issued identification number. Those two pieces of information sit side by side and act as the label for the state and local wage and withholding figures reported in Boxes 16 through 20 just below.
What Box 15 Shows
The left side of Box 15 is a two-letter postal abbreviation for the state whose tax rules apply to the numbers on that row. The right side is the employer’s state ID number, assigned by that state’s department of revenue. It is not the federal Employer Identification Number in Box b, even though the two can look similar.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3
State revenue agencies use the state ID number to match the withholding your employer deposited against the wages your employer reported. If your employer recently registered in a new state and hasn’t received its ID yet, Box 15 may show a temporary notation, with the real number appearing later on a corrected form.
How Box 15 Connects to the Rest of the Row
Box 15 is a header. Everything on the same row belongs to the state named in that box:
- Box 16 is state wages, the portion of your earnings subject to that state’s income tax.
- Box 17 is the state income tax your employer withheld and sent to that state.
- Box 18 is local wages subject to a city, county, or school district tax.
- Box 19 is the local income tax withheld.
- Box 20 names the locality that levied the local tax.
The W-2 has room for two state rows on a single form. When two different state abbreviations appear in Box 15, each row’s numbers apply only to that row’s state, and you file each state’s return using the figures from its own row.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3
Why State Wages Often Don’t Match Federal Wages
A common surprise: Box 16 doesn’t equal Box 1. That’s usually normal. States and the federal government treat certain pre-tax deductions differently. A 401(k) contribution reduces your federal taxable wages, but some states, such as Pennsylvania, do not allow that deduction, so Box 16 comes out higher. Pre-tax transportation benefits can create a similar gap where a state taxes what the federal government excludes.
If you worked in more than one state, each state’s Box 16 reflects only the wages earned in that state, so no single Box 16 will equal Box 1. On your state return, use the Box 16 amount for that state, not the federal figure.
Multiple States on Your W-2
When you worked in more than one state during the year, your employer reports each state on a separate row in Boxes 15 through 20. If you had wages in three or more states, you’ll receive additional W-2 forms to cover the rest.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3
The general rule is that state income tax is withheld for the state where you physically perform the work, not where your employer is headquartered. If you live in one state and commute to another, Box 15 typically shows the work state. Two situations change that result.
Reciprocity Agreements
Some neighboring states have reciprocity agreements for cross-border commuters. When one applies, your employer withholds only for your home state even though you physically work across the state line. Box 15 shows your home state’s abbreviation and ID, and Box 17 reflects what was sent to that home state.
Reciprocity usually requires you to file an exemption form with your employer certifying that you live in the reciprocal state. Without that form, your employer may default to withholding for the work state, leaving you to file a nonresident return there to recover the money while still paying your home state what you owe. Roughly 20 states participate in at least one such agreement, so check with your employer or your home state’s revenue department to confirm whether your specific pair qualifies.
The Convenience-of-the-Employer Rule
Remote workers can see an unexpected state in Box 15. A handful of states, including New York, Pennsylvania, Delaware, and Nebraska, along with a limited version in Connecticut and Oregon, apply what’s called the convenience-of-the-employer rule. If you work remotely for your own convenience rather than because your employer requires it, your wages can be taxed as if you earned them at the employer’s office. In that case Box 15 may show the state where the office sits, not the state where you actually sat at your desk.
The line turns on necessity. If your employer requires remote work, for instance because there’s no office near you, the rule generally does not apply and your wages should be sourced to the state where you physically worked. Only a small number of states follow this approach, so most remote employees will see their actual work state.
When Box 15 Is Blank
A blank Box 15 is not automatically a mistake. Nine states impose no state income tax on wages: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, and Wyoming. If you lived and worked in one of them, your employer has nothing to report and the entire state section will be empty.
If you worked in a state that does tax wages and Box 15 is still blank, something went wrong. The employer may have failed to register with that state’s revenue department, or payroll made an error. Do a few things:
- Contact your employer’s payroll department and ask for a corrected W-2 (Form W-2c) with the proper state information.
- Check your year-end pay stub, which usually breaks out state withholding and confirms whether tax was actually taken from your paychecks.
- Don’t delay filing. If the correction doesn’t arrive in time, Form 4852 lets you file with estimated figures.
Fixing an Error in Box 15
When Box 15 shows the wrong state, an incorrect state ID number, or wage and withholding figures that don’t match reality, your employer should issue Form W-2c, the official correction form.2Internal Revenue Service. About Form W-2 C, Corrected Wage and Tax Statements Reach out to payroll as soon as you spot the problem. The W-2c replaces the original in both your records and the state’s.
If your employer is unresponsive, unreachable, or out of business, you can file Form 4852 as a substitute W-2. The IRS expects you to make a genuine effort to get the correct form first, including calling the IRS at 800-829-1040 for help if nothing has arrived by the end of February.3Internal Revenue Service. Form 4852 – Substitute for Form W-2, Wage and Tax Statement, or Form 1099-R On Form 4852 you’ll estimate your state wages and withholding from your final pay stub, explain how you arrived at the numbers, and describe your attempts to obtain the correct W-2. Filing with estimates may slow processing while the agencies verify your return, but it beats missing the deadline.
You aren’t penalized for your employer’s mistake, but an uncorrected error can hold up your state refund or generate a notice asking you to reconcile the mismatch. Keep copies of your pay stubs and any correspondence with payroll in case questions come up later.