Please help! I am a plumber and live in NH. I have worked for two different companies which are based in MASS. One company I only worked in NH and they were taking out MASS tax until I asked them not to, they already took out 800.00. But they did provide me with a letter stating that I worked 0 days in MASS and 120 days in NH. The other company did have me work in MASS and took out state tax but when they sent me to NH they stopped taking MASS state tax but they have not provided me with a letter stating how may days I worked I worked in each state. Confusing ? How should I file MASS state tax form ? And do I get my 800.00 dollars back.

If you work (or work and live) in two different states, you will file tax return in both the states.
Any income earned while present in a state must be reported to that state.

In the state where you live, you must report your worldwide income during the period. Also in this state claim credit for the taxes paid to the other state. Your U.S. Tax Return: Working or Living in Two or More states