Working across state lines: multi-state filing for professionals

Why one job can mean several returns

If you live in one state and earn money in another, you may owe returns to both. That’s common for consultants who travel to client sites, contractors who work remotely for out-of-state companies, physicians who take locum tenens shifts, and attorneys or CPAs licensed in more than one place.

The basic idea is simple. Your home state generally taxes all of your income, wherever you earned it. Other states can tax the portion sourced to them. The details are where guessing gets expensive, because each state writes its own rules and they don’t always fit together.

Resident, nonresident, part-year

Your status in each state drives everything else, and you can hold different statuses in different states in the same year.

• Resident: you’re domiciled in the state (it’s your true, permanent home), or you meet its statutory residency test. You report all income.
• Nonresident: you live elsewhere but earned income sourced to the state. You report only that income, though many states use your total income to set the rate.
• Part-year resident: you moved in or out during the year. Income is generally split by the dates you lived there.
• Statutory residents: some states treat you as a full resident even if you’re domiciled elsewhere. New York, for example, does so if you keep a permanent place of abode there for substantially all of the year and spend 184 days or more in the state, counting any part of a day as a day.

How the credit prevents double tax, with numbers

When two states tax the same income, your resident state usually gives you a credit for tax paid to the other state. The credit is typically limited to what your home state would have charged on that same income, so if the other state’s rate is higher, you pay the difference.

Example with illustrative flat rates: you live in State A (5%) and earn $200,000, of which $60,000 is for work performed in State B (6%). State B taxes the $60,000: $3,600. State A taxes all $200,000: $10,000, then credits the lesser of the tax paid to B ($3,600) or A’s tax on that income ($3,000). You owe A $7,000 and B $3,600, for $10,600 in total. The extra $600 is the rate difference, not double tax.

Flip the rates and the credit fully offsets B’s tax, so your total is the same as if you had earned everything at home. Real calculations are messier because of graduated brackets, different definitions of income, and deductions that don’t match, which is why the nonresident return is usually prepared first and the resident return second.

Reciprocity, no-tax states, and local taxes

Some neighboring states have reciprocity agreements for wages, which let you file and pay only in your home state. They usually cover W-2 wages, not business, rental or 1099 income, and you often need to give your employer an exemption form so the wrong state isn’t withheld.

Nine states don’t tax wage income: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington and Wyoming. New Hampshire’s tax on interest and dividends was repealed for periods beginning January 1, 2025, and Washington imposes a separate tax on certain long-term capital gains. Living in one of these states simplifies your resident return, but it doesn’t stop other states from taxing income you earn there, and you get no credit to offset it.

Some cities, counties and school districts levy their own income taxes, and they have their own filing and withholding rules.

Traps that catch professionals

A handful of rules cause most of the surprises.

• Convenience-of-the-employer rules: New York treats a nonresident’s days working from home for a New York-based employer as New York workdays unless the employer has established a bona fide office at the remote location. A few other states have similar rules.
• Sourcing 1099 and business income: some states source service income to where the work is performed, others to where the customer receives the benefit. A consultant living in one state and serving clients in three may have filing obligations in all four.
• Pass-through owners: an S corp or partnership doing business in several states files in each, and may withhold or file composite returns for nonresident owners. Your K-1 should show the state breakdown; don’t ignore it.
• Entity-level tax elections: many states let S corps and partnerships elect to pay state tax at the entity level. For 2026, the individual state and local tax deduction is capped at $40,400 ($20,200 married filing separately) and reduced once modified AGI exceeds $505,000, though not below $10,000. That makes these elections worth modeling for high-earning owners.
• Estimated payments: each state where you expect to owe has its own estimates and due dates. Federal estimates don’t cover them.
• Wrong withholding: remote employees are often withheld for the employer’s state only. Check your W-2 state boxes before filing.

Moving states mid-year

A move usually means two part-year resident returns. Income earned before the move generally belongs to the old state, income after to the new one, and some items like bonuses, deferred compensation or the sale of a business need special attention.

Changing domicile is about actions, not declarations. High-tax states look at the whole picture when residency is questioned, and audits of people who move to a lower-tax state are common.

• A new lease or closing documents, and a sale or lease of the old home if applicable
• Driver’s license, vehicle registration and voter registration in the new state
• Where your family lives, where your doctors are, and where you keep items of sentimental value
• A day-count record for the year of the move and the year after

What to keep as you go

Multi-state returns are built on evidence. A simple travel calendar noting where you worked each day, plus invoices tagged by client location, makes allocation defensible and much faster at year-end.

Consider a physician who lives in one state and works 30 locum tenens shifts across two others. Each shift’s pay is generally sourced to the state where it was worked, so there may be two nonresident returns plus the resident return with credits. Contracts, shift schedules and payment stubs by facility make that allocation straightforward; a single year-end 1099 with no breakdown does not.

For employees, keep your own record of remote and in-office days; employer records don’t always match reality. For owners, keep the state apportionment data your business uses, since your personal returns depend on it.

Getting the order right

The usual sequence: identify every state with a filing requirement, determine your status in each, source income to each state, prepare nonresident returns, then prepare the resident return and claim the credit. Estimated payments for next year follow from those numbers.

Rules differ meaningfully by state and change often. When Tally Tax takes on a multi-state client, the first step is mapping filing obligations and estimate schedules before the first payment of the year is due, not after the returns are late.

Frequently asked questions