What actually happens
An employee who lives in New Hampshire and performs work in Massachusetts sits in two tax systems at once. The residence state claims the right to tax all of a resident's income wherever earned; the work state claims the right to tax income sourced within its borders. Absent an agreement, both claims stand, and the conflict is resolved after the fact through a credit on the resident return rather than up front in payroll.
When Massachusetts withholding starts
Massachusetts requires withholding from the first dollar of in-state compensation. There is no de minimis day count to shelter a short assignment. Withholding required from the first dollar of Massachusetts-source wages; no de minimis day or dollar safe harbor.
The trap is that thresholds are usually retroactive to the first day once crossed. An employee who spends 40 days in a 30-day-threshold state does not owe tax on 10 days; they owe it on all 40, and the employer is the one who failed to withhold.
Unemployment insurance goes to one state only
Income tax can be split between states. Unemployment insurance cannot. Under the localization test used by every state, an employee whose services are performed entirely in Massachusetts is covered by Massachusetts for unemployment purposes, and all wages are reported there — regardless of where they live, where you are headquartered, or which state's income tax you withhold. Massachusetts's 2026 taxable wage base is $15,000. The four-factor test in order.
What you have to register for
| Obligation | State | Agency |
|---|---|---|
| Income tax withholding | Massachusetts | Massachusetts Department of Revenue |
| Unemployment insurance | Massachusetts | Massachusetts Department of Unemployment Assistance (DUA) |
| Paid family & medical leave | Massachusetts | Massachusetts PFML 2026 total contribution is 0.88% of eligible wages up to the Social Security wage base. Employees pay up to 0.18% for family leave and up to 0.28% for medical leave (0.46% combined); employers with 25+ covered individuals pay the remaining 0.42% of medical leave. |
Frequently asked
Do Massachusetts and New Hampshire have a reciprocal tax agreement?
No. There is no reciprocal agreement between Massachusetts and New Hampshire. Massachusetts taxes wages earned in the state by nonresidents, and New Hampshire does not tax wages at all.
Which state's income tax should be withheld?
Massachusetts, as the state where the work is performed. New Hampshire imposes no wage income tax, so Massachusetts is the only withholding obligation.
Which state gets the unemployment insurance wages?
Massachusetts. Unemployment coverage is never split between states for a single job. The localization test assigns the whole job to the state where services are performed, which here is Massachusetts, regardless of residence or where the employer is headquartered.
How many days can an employee work in Massachusetts before withholding starts?
There is no safe harbour. Massachusetts requires nonresident withholding from the first dollar of compensation earned in the state, so even a single day of in-state work creates an obligation in principle.