Determination engine

Which state do you actually withhold in?

Reciprocity, convenience-of-the-employer, nonresident thresholds and unemployment localization, applied together to one employee's facts. Every answer cites the state source it came from.

Withhold Massachusetts income tax.

The work state does not tax these wages, so the residence state governs.

Income tax withheld to

Massachusetts

Graduated, top rate 9%

Employee certificate

None required

No state withholding allowance certificate applies.

Unemployment insurance

Connecticut

Localized under factor 1: Localization.

Reciprocal agreement

Connecticut has no reciprocal agreements.

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Below the Connecticut nonresident threshold

Connecticut does not require nonresident withholding until the employee exceeds 15 working days in the state. You entered 0. Per Circular CT (IP 2026(1)): 'If a nonresident employee performs personal services for employment purposes in Connecticut for 15 days or less, this compensation is not Connecticut-sourced income and is not subject to Connecticut income tax.' If the employee ends up exceeding 15 days, withholding applies retroactively to ALL Connecticut compensation. Tax Foundation separately reports a >$6,000 nonresident filing threshold.

Track this, because it flips mid-year

Once the threshold is crossed, most states require withholding on all in-state wages for the year, not just the excess. Set an alert well before the limit.

Massachusetts also taxes this income, with a credit

The residence state taxes worldwide income. The employee claims a credit on the Massachusetts return for tax paid to Connecticut, which prevents true double taxation but usually still leaves a balance if Massachusetts's rate is higher. Some employers withhold for both states; many withhold only for Connecticut and let the employee manage the difference.

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Connecticut paid family and medical leave contributions

Connecticut Paid Leave is 100% employee-funded at 0.50% of wages up to the Social Security wage base ($184,500 for 2026). The CT Paid Leave Authority held the rate at 0.50% for 2026. Employee contribution: 0.5%. These follow the state of unemployment coverage, not the income tax state.

Massachusetts also runs a paid leave program

The employee resides in Massachusetts, which has a mandatory paid leave program, but unemployment coverage is localized to Connecticut. Check whether Massachusetts requires coverage based on residence; several programs use a work-location test and a few do not.

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Employer registrations you will need

Massachusetts — Income tax withholding: Massachusetts Department of Revenue
Connecticut — Unemployment insurance: Connecticut Department of Labor

Connecticut profile Massachusetts profile Full write-up for this pair

Change the inputs

Withholding determination

Answer six questions. The result is a shareable link, so you can paste it into a ticket or an email.

Employee lives inState of residence

Work is performed inWhere the employee physically sits

Employer is based inWhere the work is directed from

Days in the work stateThis calendar year, leave blank if unknown

Wages from work-state daysUS dollars, leave blank if unknown

Arrangement Works remotely rather than at an employer location Remote work is an employer necessity, not employee preference

Run a whole roster instead

This is a determination aid, not advice. StateSide encodes published state rules and applies them mechanically to the facts you enter. It does not know your entity structure, your nexus history, your equity compensation, or the dozens of exceptions that turn a clean rule into a judgement call. Every determination cites the state source it came from — verify against that source, and take anything consequential to a payroll tax professional before you act on it.