State and local income tax payroll deductions work by having your employer calculate a percentage of your gross wages using your state’s tax tables (and, where applicable, your city or county’s rate), then sending that money directly to the taxing authority before you ever see your paycheck. The exact amount depends on where you live, where you physically work, your filing status, the allowances or adjustments you’ve claimed on your state withholding form, and any pre-tax deductions that reduce your taxable wages before the calculation runs. Forty-two states withhold income tax from wages, and roughly 5,000 local jurisdictions across 17 states layer their own income or earnings taxes on top.
If you both live and work in Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, or Wyoming, you won’t see a state income tax line on your pay stub at all.1Tax Foundation. State Individual Income Tax Rates and Brackets, 2026 Washington taxes capital gains but not wages, and New Hampshire doesn’t tax earned wages either. Everyone else deals with the mechanics below.
What Your Employer Actually Calculates
Federal law obligates your employer to withhold income tax from wages, and states with an income tax piggyback on that system by requiring a parallel state-level calculation using their own brackets or flat rates.2Office of the Law Revision Counsel. 26 USC 3402 – Income Tax Collected at Source Some states use graduated brackets like the federal structure. Others use a single flat rate on all taxable wages.
Four variables drive the number on your pay stub:
- Gross wages. Your total pay before deductions is the starting point. In graduated-rate states, higher earnings push part of your income into higher brackets.
- Filing status. Single, married filing jointly, and head of household each use different income thresholds. Married filing jointly typically results in less tax withheld per dollar earned because the brackets are wider.
- Allowances or adjustments. On your state withholding form, you either claim a number of allowances or enter specific dollar-amount adjustments. Each one reduces the portion of your wages subject to withholding.
- Pay frequency. Payroll annualizes each check to figure out which bracket applies. A biweekly check gets multiplied by 26, a monthly check by 12. Same math, different per-check amount.
This is why two coworkers with identical salaries can take home different amounts. The salary is only one input.
Pre-Tax Deductions That Shrink the Taxable Base
Certain deductions come out of your paycheck before state income tax is calculated, which lowers withholding directly. In most states, these include:
- Traditional 401(k) and 403(b) contributions. These reduce state taxable wages in the vast majority of states. New Jersey is a notable exception — it taxes traditional retirement contributions when they’re made rather than when they’re withdrawn.
- Employer-sponsored health insurance premiums paid through a Section 125 cafeteria plan. Excluded from federal and state taxable income in nearly every state.
- Health savings account contributions made through payroll. Bypass federal income tax and most state income taxes, though a small number of states don’t recognize the HSA exclusion.
- Flexible spending account contributions. Same treatment as HSA contributions for federal and most state purposes.
The practical consequence: raising your 401(k) contribution drops your state withholding along with your federal withholding, so the real cost of contributing is smaller than the dollar amount leaving your check.
Local Taxes on Top of State Withholding
Seventeen states and the District of Columbia let cities, counties, school districts, or other local jurisdictions impose their own income or earnings taxes. These appear on pay stubs under labels like Earned Income Tax, Local Services Tax, or Occupational Privilege Tax. Some are a small percentage of earned income. Others are flat-dollar amounts deducted monthly or annually. Rates range from fractions of a percent up to nearly 4% in the highest-taxing cities.
Whether you’re a resident or a commuter usually matters. Many localities charge residents a higher rate and non-residents a lower one. Some apply the same rate to both. A few tax residents only and let commuters off entirely.
Your employer has to identify the exact political subdivision of both your home and your work location, because neighboring towns a few miles apart can have completely different rates or no local tax at all. If the wrong local withholding is applied, you could end up owing the local tax bureau directly when you file. Low-income workers often qualify for exemptions from flat-dollar local taxes; many jurisdictions exempt employees whose total expected annual earnings fall below $12,000.
Why Overtime and Bonus Checks Look Wrong
When you get a big overtime check or a one-time payment, payroll typically treats that inflated check as though you earn that amount every pay period. A $5,000 biweekly check gets annualized to $130,000 even if your base salary is $60,000. The withholding percentage jumps accordingly, then corrects itself over the rest of the year through your normal checks. That’s the usual reason a large overtime paycheck comes in smaller than expected.
Bonuses, commissions, and severance are treated as supplemental wages and handled somewhat differently. Federally, employers can apply a flat 22% withholding rate on supplemental wages up to $1 million per year, with a mandatory 37% rate above that.3Internal Revenue Service. 2026 Publication 15-T – Federal Income Tax Withholding Methods Many states offer their own flat supplemental rate. Others require employers to use graduated tables for bonuses, which is why a $20,000 bonus paid in a single check can produce eye-watering withholding — the system annualizes the bonus check as though you earn $520,000 a year. You’ll recover the excess when you file, but the immediate hit is real.
Living in One State and Working in Another
The baseline rule for cross-border workers: you owe income tax to the state where you physically perform the work, and your home state also taxes your worldwide income. Double taxation is generally avoided through credits, with your home state giving you credit for tax paid to the work state.
Reciprocal Agreements
About 17 states and the District of Columbia have reciprocal agreements with neighbors that eliminate dual withholding for commuters. Under a reciprocal agreement, your employer withholds only for your home state even though you cross a state line to work. You have to file an exemption certificate with your employer to activate the arrangement; it doesn’t happen automatically. Without that form, your employer withholds for the work state and you file a nonresident return to get the money back.
Reciprocal agreements typically cover only wage and salary income. If your home and work states don’t have one, you’ll file returns in both and claim the credit on your resident return.
Convenience of the Employer
Remote work introduces a wrinkle in about seven states. Under a “convenience of the employer” rule, if your company’s office is in that state and you work remotely from your home in another state, the employer’s state can still tax your full wages unless the remote setup is a documented business necessity rather than your personal choice. New York is the most prominent enforcer and applies a detailed multi-factor test to the question.4New York State Department of Taxation and Finance. New York Tax Treatment of Nonresidents and Part-Year Residents The burden of proof sits with the employer. If your company is headquartered in one of these states, check whether they’re already withholding for it, because you can end up temporarily out of pocket while your home-state credit sorts itself out at filing time.
Adjusting Your State Withholding
More than 30 states use their own withholding form separate from the federal W-4. Some still use the older allowance-based system. Others have moved to a format that mirrors the redesigned federal W-4 with dollar-amount adjustments. Each asks for your home address, Social Security number, and either a number of allowances or a specific additional withholding amount. You can also use the form to request extra withholding per check if you have side income (freelance work, investment gains) that isn’t subject to payroll withholding on its own.
Update the form after any life change that shifts your tax picture: marriage, a new child, a home purchase, a spouse losing income, starting a side business. You can generally update at any time, though decreases in allowances often need to be reported within 10 days in states that follow federal timing rules. Changes usually take effect within one or two pay cycles. Check the next pay stub to confirm the new amount, and contact payroll immediately if something looks off. A clerical error caught early is much easier to fix than one discovered at filing time.
Claiming Exemption
Some employees qualify for a complete exemption from state withholding. The criteria vary by state but commonly include being under a certain age, being a full-time student under 25, being over 65, or earning below the state’s filing threshold. Claiming exemption typically requires certifying that you had no state tax liability last year and don’t expect any this year. Exemption claims usually expire at year-end, so refile annually. Miss the deadline and your employer will start withholding at the default rate, which is normally the highest rate for a single filer with zero allowances.
When Withholding Isn’t Enough
If your withholding doesn’t cover your actual liability, you owe the balance at filing time, and if the shortfall is large you may also face an underpayment penalty. Most states follow the same safe harbor framework the IRS uses: you avoid the penalty if you’ve paid at least 90% of the current year’s tax liability or 100% of the prior year’s, whichever is less.5Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty Higher-income filers, generally those with adjusted gross income above $150,000, usually need to cover 110% of the prior year’s tax to hit the safe harbor.
When you know withholding won’t be enough because of substantial investment, rental, or freelance income, the fix is quarterly estimated payments directly to the state. Most states align their quarterly deadlines with the federal schedule: April 15, June 15, September 15, and January 15 of the following year. Missing those triggers the same type of penalty as under-withholding.
The penalty is calculated as an interest charge on the shortfall for each quarter you were underpaid. It’s not catastrophic for a one-time miss, but it compounds quickly if ignored for an entire year. If you owed a large balance last April, the simplest response is to raise your state withholding or start estimated payments now rather than waiting for the pattern to repeat.