All wages you earn as a Massachusetts resident are taxable to Massachusetts, even if you work out of state. Typically, there is withholding reported for both states in this situation. Some employers will list the amounts earned in and out of Massachusetts in different boxes of Form W-2 Wage and Tax Statement.
This can cause an issue for residents using MA Form 1, because the wages were listed twice on the W-2, so they are now also listed twice on MA Form 1.
The Massachusetts Department of Revenue recommends that you request a corrected W-2 from your employer showing only the amounts in Box 16 attributable to the state in which they are earned.
If the employer will not issue a corrected Form W-2, there are a couple options available to complete your tax return reporting the correct amount of wages that are taxable to Massachusetts.
Option 1: (Paper filing only, E-File not allowed)
The first option to correct this issue is to make the adjustment reducing the amount of wages directly on Line 3 using the Wage Adjustment Field.
Enter a negative adjustment in the amount of the wages that were duplicated on Form W-2. This will properly report the amount of wages taxable to Massachusetts. When using this option, you are not allowed to e-file because Massachusetts will reject the return due to total wages in Box 16 of Form W-2 being lower than the amount reported on Line 3.
Option 2: (E-File Allowed)
If you want to electronically file your return and cannot get a corrected W-2, you can adjust the amount of wages on Form W-2, Box 16 to properly reflect the amount of wages that are taxable to Massachusetts. In this case where wages are doubled in Box 16 of the W-2, you will manually need to make an adjustment to each states' Box 16 so that the total wages reported in all Box 16s are equal to the total amount of state wages earned.
When you make this adjustment, you should generally adjust the W-2 so that Box 16 for each state reflects the total amount of wages earned in each state.
Note. You will want to verify the correct amount is still reported on any other state's return that you may also be attached to your return.