The credit for taxes paid to another state is the lesser of two figures: the tax you actually paid to the nonresident state on the income both states are taxing, or the tax your home state would have charged on that same income. You claim it on a schedule attached to your resident return, and you cannot fill that schedule out correctly until the nonresident return is finished.
When the Credit Applies
The credit exists to prevent the same dollar of income from being fully taxed by two states. Your home state claims the right to tax everything you earn, wherever you earn it. A nonresident state can tax the portion of your income sourced to activity within its borders. Without a credit, both claims would stack and you would pay twice.
The typical case is a W-2 employee who lives in one state and commutes to work in another. It also covers real estate investors who sell property in another state, rental income from out-of-state property, and business owners with cross-border operations.
Two situations take the credit off the table before you calculate anything. First, if either state involved has no broad-based personal income tax, there is nothing to credit. Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, and Wyoming impose no such tax. If you live in one of these, you have no home-state liability to offset. If you earn in one of these, no tax was paid to the other jurisdiction.
Second, if your home state and work state have a reciprocity agreement, the work state does not tax your wages at all and there is nothing to credit. Roughly 16 states and the District of Columbia have reciprocity with at least one neighbor. Common pairs include Pennsylvania and New Jersey, Virginia and Maryland, and Illinois with several neighbors. Reciprocity only works if you file a withholding exemption certificate with your employer using the work state’s form; skip that step and you will still have tax withheld and need a nonresident return to recover it. Reciprocity also covers wages and salary only. Business income, rental income, and other non-wage earnings sourced to the work state remain subject to the standard credit calculation.
Which Income the Credit Covers
The credit only applies to income both states tax. Getting the sourcing right is what makes the calculation work.
For W-2 wages, income is sourced to the state where you were physically working when you earned it. If you split time, you allocate by workdays. Someone with 200 workdays in the home state and 50 in another state sources 20 percent of salary to the nonresident state. That allocation ratio drives everything downstream, so a workday log is worth keeping.
Interest, dividends from publicly traded stocks, and capital gains on securities are sourced to your home state and never enter the credit calculation. The main exception is real property. Gains from selling land or a building in another state, and rental income from out-of-state property, are sourced to the state where the property sits and do qualify for the credit.
The Convenience of the Employer Trap
Six states apply some form of a “convenience of the employer” rule: Connecticut, Delaware, Nebraska, New Jersey, New York, and Pennsylvania. If you work from home for your own convenience rather than because your employer requires it, these states treat your income as sourced to the employer’s office regardless of where you were sitting.
Your home state still sees you working within its borders and taxes you. The employer’s state also taxes you under the convenience rule. Whether your home state gives full credit depends on whether it recognizes the convenience rule as a valid basis for the other state’s claim. In some pairings the result is genuine double taxation with no complete remedy, and this is the area of state tax law that generates the most complaints.
Step One: Finish the Nonresident Return First
The credit uses the actual tax liability shown on the completed nonresident return, not the amount withheld from your paychecks and not what estimated payments came to. That figure only exists once the nonresident return is finalized, so it has to be done first. Tax software is built to process returns in this order; manual filers sometimes get it backward.
Most states calculate a nonresident’s tax in two steps. They first compute the tax as if your entire income were taxable in that state, applying the full rate schedule to your total income. Then they multiply that figure by an allocation percentage equal to your in-state sourced income divided by your total income. The result is the tax attributable to what you actually earned there, but at the marginal rate corresponding to your overall income level. Someone with $150,000 total income and $40,000 sourced to the nonresident state pays at the rate appropriate for a $150,000 earner, not the lower rate that would apply if $40,000 were the only income.
Step Two: Run the Lesser Of Test
On your resident return, the credit is the lesser of two amounts:
- Amount A: the actual tax you paid to the nonresident state on the double-taxed income, taken from the completed nonresident return.
- Amount B: the tax your home state would have charged on that same income.
Amount B is a hypothetical calculation. Divide your total home-state tax liability (before the credit) by your total taxable income to get an effective rate, then multiply that rate by the income sourced to the other state.
A worked example. Total income is $120,000. Your home state’s tax on that amount is $6,000. Of your income, $45,000 was sourced to the work state, and the work state charged $3,100 on it. Your home-state effective rate is 5 percent ($6,000 ÷ $120,000). Amount B is $2,250 ($45,000 × 5%). Amount A is $3,100. The credit is $2,250, the lesser figure.
The practical result is that you always end up paying at least the higher of the two states’ rates on the shared income. When the work state charges more than your home state would, the credit covers only your home state’s share and the excess paid to the work state is gone. When the work state charges less, the credit equals the full nonresident tax and you pay the difference to your home state. Either way, you land at the higher rate.
The Credit Cannot Generate a Refund
One more ceiling applies. The credit can never exceed your total home-state tax liability. It is nonrefundable in virtually every state: it can zero out your home-state bill but cannot produce a refund on its own. If the tax you paid to the other state is larger than what your home state would have collected on your entire return, the excess is not recoverable.
Reverse Credit States Flip the Procedure
Most states follow the standard model where the home state grants the credit. A handful flip this and grant the credit on the nonresident return instead. Arizona, California, Indiana, and the District of Columbia are among these “reverse credit” states. You file the resident return first, and then the nonresident state reduces its tax by crediting what you paid to your home state. The math is the same. The order of filing and the return that carries the credit are reversed. If your work state is on that list, read the nonresident instructions carefully, because claiming the credit on the wrong return is a common and avoidable mistake.
Pass-Through Entity Tax and Local Taxes
If you own an interest in a partnership or S-corporation that elected a state pass-through entity tax, the credit picture gets messier. When the entity pays PTET to one state and you live in a different state, your home state’s treatment varies. Some states let you claim a personal credit for PTET the entity paid to another state. Others require the credit at the entity level. A few exclude PTET-taxed income from your personal tax base entirely, making the credit unnecessary but requiring careful tracking. Refundability also varies: some states allow excess PTET credits to be refunded, others only allow carryforward. When the entity-level PTET rate in the other state exceeds your home state’s individual rate, you may not be able to fully use the credit. This is one of the situations where a professional genuinely pays for themselves.
Local income taxes are a similar question. Cities like Philadelphia, New York City, and several in Ohio impose their own income tax on top of the state tax. Some home states treat the local tax as creditable, others limit the credit strictly to state-level income taxes. Where local taxes are excluded, you face real double taxation on that portion with no offset. Check your home state’s credit instructions before assuming a city tax counts.
How to Actually File the Credit
The credit is never applied automatically. You claim it on a schedule attached to your resident state return, and each state has its own version of that form. The schedule walks through the lesser-of calculation using figures from the completed nonresident return, and the resulting credit flows onto the main state form to reduce your balance.
Most states require a full copy of the nonresident return, including all supporting schedules, to be attached to your resident filing as proof of the tax paid. Submitting the resident return without the nonresident attachment is one of the most common reasons the credit gets denied or delayed.
A few other mistakes recur:
- Filing in the wrong order. Complete the nonresident return first (unless you are in a reverse-credit situation). You cannot fill in the credit schedule without the final nonresident liability.
- Using withholding instead of liability. The credit is based on the tax calculated on the nonresident return, not what your employer withheld. Withholding is an estimate.
- Including income the work state did not tax. Only income taxed by both states qualifies. Interest and dividends your home state taxes but the work state does not cannot be included.
- Forgetting the credit entirely. If you missed it on your original return, an amended return can claim it. Most states allow amendments for at least three years from the original due date, though the window varies.
For straightforward W-2 income split between two states, the credit is tedious but manageable in tax software. Add convenience-of-employer sourcing, a PTET election, or income tied to three or more states, and the interactions multiply fast. Interest on underpaid state taxes commonly runs between 7 and 14 percent annually, so the cost of getting it wrong often exceeds the cost of professional help.