State and local wages on a W-2 are different from federal wages because each level of government writes its own definition of taxable pay. Box 1 shows your federal taxable wages, Box 16 shows your state taxable wages, and Box 18 shows your local taxable wages. All three start from the same salary, but each applies its own rules about which pre-tax deductions and fringe benefits reduce what you owe. When your state or city doesn’t recognize a deduction the federal government allows, that deduction gets added back, and the wage figure grows.
Pre-Tax Deductions Are the Usual Reason Box 16 Doesn’t Match Box 1
The gap between federal and state wages almost always traces back to pre-tax deductions your employer withheld from your paycheck. Federal cafeteria plans let you pay for health insurance, flexible spending accounts, and similar benefits with pre-tax dollars, so those amounts never appear in Box 1.1Internal Revenue Service. FAQs for Government Entities Regarding Cafeteria Plans Most states follow that treatment, so health premiums typically reduce Box 1 and Box 16 by the same amount. The trouble starts with retirement contributions.
Money you put into a 401(k) or 403(b) is excluded from Box 1.2Internal Revenue Service. Topic No. 424, 401(k) Plans A few states, most notably Pennsylvania, don’t recognize that exclusion. There, every dollar you defer into a 401(k) gets added back into Box 16. Contribute $10,000 for the year and Box 16 will run $10,000 higher than Box 1 on the same salary.
Health Savings Account contributions cause the same problem in a smaller group of states. The federal government treats HSA contributions as tax-free, but California and New Jersey don’t. Pennsylvania partially conforms: employer contributions and employee contributions made through a cafeteria plan are excluded from state wages, but direct employee contributions are not.3Commonwealth of Pennsylvania. Health Savings Accounts; Withholding If you contribute to an HSA in one of these states, expect Box 16 to sit above Box 1.
Other Fringe Benefits States May Tax Differently
Retirement and HSA money aren’t the only add-backs. States can define taxable compensation more broadly than federal law for several fringe benefits.
- Educational assistance. Federal law excludes up to $5,250 a year in employer-provided educational assistance from taxable income. A state that doesn’t follow the exclusion will include some or all of that tuition benefit in Box 16.4Office of the Law Revision Counsel. 26 USC 127 – Educational Assistance Programs
- Group term life insurance. The federal government excludes employer-paid coverage up to $50,000. Amounts over that already show up in Box 1. Some states set a lower threshold or provide no exclusion, so Box 16 climbs.5IRS.gov. 2026 Publication 15-B Employer’s Tax Guide to Fringe Benefits
- Adoption assistance, transit benefits, and similar perks. A few states treat these as taxable even when federal law excludes them.
Because the rules vary state by state, there’s no universal formula. Your final year-end pay stub is the fastest check: it usually breaks out which pre-tax deductions applied to federal wages versus state wages. If Box 16 is higher than Box 1, the difference will normally line up with the deductions your state doesn’t recognize.
Working in More Than One State
If you worked in more than one state during the year, whether from a relocation, a cross-border commute, or business travel, your W-2 may show separate Box 16 entries for each state. Box 1 always reports your total federal wages regardless of location. Each state, though, only taxes the wages tied to work performed there, and your employer allocates accordingly. The sum of your Box 16 amounts may or may not equal Box 1 depending on how each state’s rules interact.
Reciprocal Agreements
Many neighboring states have reciprocal agreements for cross-border commuters. Under one, your employer withholds state tax only for the state where you live, not where you work.6National Finance Center. Processing and Changing State Taxes In that situation, Box 16 for the work state may be blank or zero even though you spent every workday there. Only your home state’s wages appear.
The Convenience-of-the-Employer Rule
A handful of states, including New York, Pennsylvania, Delaware, Connecticut, Nebraska, and Oregon, apply a “convenience of the employer” test that can catch remote workers off guard. If you work from home in another state for your own convenience rather than because your employer requires it, your wages may still be taxed by the state where the office is located. Box 16 can end up showing wages for a state you never physically set foot in during the year. Double taxation is possible if your home state doesn’t offer a full credit for the tax paid to the office state. If you work remotely across state lines, check whether either state applies this rule before you file.
Why Box 18 Is Often the Highest Wage Figure
Box 18 reports wages subject to local income tax, and it frequently doesn’t match Box 1 or Box 16. Local taxing authorities in parts of Ohio, Kentucky, Pennsylvania, New York City, and elsewhere often define taxable income more broadly than the federal government does. Many cities and municipalities calculate their tax on gross wages and don’t allow reductions for 401(k) contributions, HSA contributions, or other pre-tax benefits.
The result: a city may tax every dollar of your compensation, including bonuses and commissions, without any of the reductions that shrink Box 1. Box 18 can end up as the highest wage number on the form. Box 19 shows the local income tax actually withheld from your paychecks against those wages. If you live or work in a locality with an income tax, comparing Box 18 to your gross pay for the year is the quickest way to confirm the number.
Why Boxes 3 and 5 Also Look Different
Since you’re already looking at the wage boxes, it’s worth knowing why Box 3 (Social Security wages) and Box 5 (Medicare wages) often exceed Box 1. This is normal. 401(k) and 403(b) contributions reduce Box 1 but stay subject to Social Security and Medicare tax, so Boxes 3 and 5 include your retirement contributions and Box 1 doesn’t.2Internal Revenue Service. Topic No. 424, 401(k) Plans If your total compensation was $75,000 and you contributed $8,000 to a 401(k), Box 1 shows roughly $67,000 while Boxes 3 and 5 show the full $75,000 minus only cafeteria-plan deductions like health insurance.
Telling a Real Error From a Normal Difference
A gap between boxes usually isn’t an error. It reflects the rule differences above. Real mistakes happen too, though. Compare your W-2 to your final pay stub for the year, add up the pre-tax deductions your state doesn’t recognize, and see whether that total explains the Box 1 to Box 16 gap. If it does, the form is right.
If something still doesn’t add up, say wages reported to a state where you never lived or worked, start with your employer’s payroll department and ask for a corrected W-2 (Form W-2c). Most errors get fixed there. If you don’t have a corrected form by the end of February, contact the IRS at 800-829-1040 or visit a Taxpayer Assistance Center.7Internal Revenue Service. If You Don’t Get a W-2 or Your W-2 Is Wrong The IRS will send your employer a letter asking for a correction. If the correction doesn’t arrive in time to file, the IRS will send you Form 4852 so you can file using your best estimate based on your pay stubs.8Internal Revenue Service. W-2 – Additional, Incorrect, Lost, Non-Receipt, Omitted
Filing with the wrong wage figure has consequences. If you underreport income because of a W-2 mistake you didn’t catch, the IRS can impose an accuracy-related penalty equal to 20 percent of the underpayment.9Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments Catching problems before filing protects you.