Locum Tenens Taxes in Massachusetts

If you are not a Massachusetts resident but earned income from services performed inside Massachusetts, you must file Form 1-NR/PY, the Nonresident/Part-Year Resident return, once your Massachusetts-source gross income exceeds the lesser of $8,000 or your prorated personal exemption. For a working physician, that threshold is a formality: any real locum assignment clears it, usually within the first few shifts.

The obligation applies whether you are paid 1099 directly, through a staffing agency, or through your own S-corp or LLC that assigns you to a Massachusetts facility. Massachusetts taxes only the Massachusetts-source portion of your income on the nonresident return, not your worldwide income, but the rate applied to that portion is the same flat 5% every resident pays.

Massachusetts sources compensation for personal services to the place where the services are physically performed. For a locum physician, that means the income tied to days you actually worked inside Massachusetts is Massachusetts-source income, no matter where you live, where the staffing agency is headquartered, or where your entity is registered. There is no minimum-day safe harbor for a paid assignment: a two-week stint at a Worcester hospital creates Massachusetts-source income for those two weeks.

When an assignment mixes states, the standard approach is a working-days allocation: Massachusetts working days divided by total working days, applied to the compensation for that engagement. Keep a day-by-day log. If your allocation is ever questioned, a contemporaneous calendar backed by credentialing records and shift schedules is what wins.

Since 2023, Massachusetts has imposed an additional 4% surtax on the portion of annual taxable income above a threshold that started at $1 million and now adjusts for inflation each year: $1,107,750 for 2026. Income above the line is taxed at a combined 9% instead of 5%. Only the excess is hit; crossing the threshold does not change the rate on the first $1.1 million.

Why does this matter to locum physicians specifically? Day rates. A locum working high-demand specialties at Massachusetts rates can gross far more than a comparable employed position, and physicians who stack heavy schedules, work multiple state licenses, or pair locum income with a working spouse's income can approach seven figures faster than they expect.

For most nonresident locums, the practical exposure is limited because the surtax is computed on Massachusetts taxable income, and few travelers source over a million dollars to Massachusetts alone. But verify the mechanics for your situation rather than assuming: physicians who are Massachusetts residents, part-year residents in a move year, or nonresidents with unusually Massachusetts-heavy years are the ones who get caught.

W-2 locum agencies generally withhold Massachusetts income tax from wages for work performed in the state, so W-2 travelers often square up automatically. 1099 independent contractors get no withholding by default. If you expect to owe Massachusetts more than $400 for the year, you are expected to make quarterly estimated payments using Form 1-ES (or through MassTaxConnect). Skip them and you can owe underpayment penalties on top of the tax.

A simple habit works: every time a Massachusetts assignment pays, move 5% of the gross into your tax savings account and earmark it for Massachusetts. Your federal set-aside is separate and larger; this is just the state layer.

On local taxes, Massachusetts is genuinely friendly: no city or town income taxes exist anywhere in the state. Compare that with Michigan, where two dozen cities levy their own income taxes, or Pennsylvania and Ohio with their local earned-income tax webs. One state return covers your Massachusetts obligations.

The standard locum S-corp math, saving self-employment tax on the distribution side of a reasonable-compensation split, works the same in Massachusetts as anywhere else. What changes is the state layer around it.

1. The elective pass-through entity excise (a good thing)

Massachusetts offers an annual election under chapter 63D that lets an S-corp or partnership pay a 5% entity-level excise on its Massachusetts-source income, with members claiming a credit equal to 90% of their share of the excise paid. Because the entity-level payment is deductible federally without the individual SALT cap, the election can convert otherwise capped state tax into a federal deduction. It is filed on Form 63D-ELT, works for residents and nonresidents alike, and is worth modeling in any year with meaningful Massachusetts profit, though the 10% haircut on the credit means it is not automatic.

2. The corporate excise on S-corps (a small drag)

An S-corp doing business in Massachusetts is subject to the state's corporate excise, which for most small S-corps means the minimum excise of $456 per year (an income-based measure applies only once total receipts reach multi-million-dollar levels that a solo locum practice will not hit). It is not California's $800-plus-1.5%, but it is a real line item, alongside registration and the S-corp's own Massachusetts filing, when you run the S-corp break-even math for a Massachusetts-heavy year.

Illustrative example, not a specific client outcome. A hospitalist who is a Colorado resident earns $320,000 of 1099 locum income for the year. She works about 25% of her days in Massachusetts and the rest in Colorado, so $80,000 is allocated to Massachusetts.