If you earn a paycheck in the United States, you are almost certainly paying two different income taxes: one to the federal government and, in most states, one to the state where you live or work. The two systems run on separate rules, separate brackets, and separate deadlines. Understanding how state income tax vs federal income tax differ — and where they overlap — helps you estimate your true tax bill, avoid underwithholding penalties, and make smarter decisions about where you live and work.
The Core Difference: Two Governments, Two Tax Codes
The federal income tax is levied by the Internal Revenue Service (IRS) under the Internal Revenue Code and applies the same way in every state. The IRS collects roughly half of all federal revenue, and the tax is progressive: rates rise as taxable income rises, with seven brackets ranging from 10% to 37% for the 2024 tax year.
State income tax is imposed by individual state legislatures. That means the rules vary dramatically from one state to the next. A state can choose its own brackets, its own standard deduction, its own credits, and even whether to have an income tax at all. There is no constitutional requirement that states mirror federal law, and most do not.
The practical result: your marginal rate on the last dollar you earn can differ sharply between the two systems, and your effective rate — total tax divided by total income — will almost always be lower at the state level.
Which States Tax Income — and Which Do Not
As of 2025, eight states impose no tax on individual wage income:
- No income tax at all: Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, and Wyoming. (New Hampshire taxes interest and dividends but not wages, and that tax is phasing out.)
- Flat-tax states: A growing group, including Colorado, Illinois, Indiana, Kentucky, Massachusetts, Michigan, North Carolina, Pennsylvania, and Utah, applies a single rate to most wage income.
- Graduated-tax states: Most others, such as California, New York, New Jersey, and Minnesota, use multiple brackets. California's top marginal rate exceeds 13%, the highest in the country.
Two states — New Hampshire and Tennessee historically — taxed only investment income, which is worth noting if you have significant dividends or interest.
Do not assume "no income tax" means "low tax overall." States without an income tax often rely more heavily on sales, property, and excise taxes, which can hit middle- and lower-income households harder.
How the Two Taxes Are Calculated Differently
Both systems start with gross income, subtract deductions, and apply rates to what remains, but the details diverge.
Deductions and exemptions
At the federal level, you choose between the standard deduction ($14,600 for single filers and $29,200 for married filing jointly in 2024) or itemizing. Many states offer their own standard deduction, and some allow you to itemize state-specific items. A few states, like Pennsylvania, offer no standard deduction at all.
What counts as income
Most states start from federal adjusted gross income or federal taxable income, then add or subtract state-specific adjustments. For example, some states exempt municipal bond interest from their own bonds, and a handful do not tax Social Security benefits even though the federal government may.
Deduction interactions
State and local income taxes (or general sales taxes) are deductible on your federal Schedule A if you itemize, subject to the $10,000 cap on state and local tax (SALT) deductions. This is one of the few places the two systems directly interact — and it is a common reason high-tax-state residents lose part of the benefit of itemizing.
Withholding, Filing, and Deadlines
Your employer withholds federal tax based on your Form W-4 and state tax based on a separate state withholding form. If you work remotely for an employer in another state, you may owe tax where you live, where your employer is located, or both — depending on reciprocity agreements. Roughly a dozen states have reciprocal agreements that prevent double taxation for commuters.
Filing deadlines generally line up: federal returns are due April 15, and most states follow the same date. A few states, such as Virginia and Louisiana, have different deadlines, so confirm your state's date each year.
If you owe tax to more than one state, you typically file a nonresident return in the state where the income was earned and claim a credit on your resident return for taxes paid elsewhere. This prevents the same income from being taxed twice, though the credit is usually limited to the lower of the two amounts.
Common Mistakes That Cost Taxpayers Money
- Assuming your state follows federal rules. State standard deductions, brackets, and credits are independent. A change in federal law does not automatically flow through.
- Ignoring state estimated taxes. If you are self-employed or have significant investment income, you may need to make quarterly payments to both the IRS and your state revenue department.
- Overlooking residency rules. States like California and New York aggressively audit residency. Spending more than 183 days in a state often triggers full-year residency and tax on all income.
- Forgetting local taxes. Some cities and counties, including New York City and many Ohio and Pennsylvania municipalities, levy their own income tax on top of state tax.
What to Remember About State vs Federal Income Tax
Federal income tax applies uniformly across the country and uses seven progressive brackets from 10% to 37%. State income tax is set independently by each state, ranges from zero to more than 13%, and can be flat, graduated, or nonexistent. Your total obligation is the sum of both, and the two systems interact mainly through the SALT deduction and multi-state filing credits. Before you move, take a remote job, or change how you earn income, check both the federal rules and the specific rules of every state that might have a claim on your income — and set aside money for quarterly payments if withholding will not cover the bill.
