I filed taxes in two states and I need to amend the tax return from one of the states. Do I need send amendment forms to both states or just the single state that I need to amend in?

No, you can just amend the one state.

To amend your state,

• Click the button beside the state you want to amend
• You will want to go through all of the state screens, past estimated taxes and extension questions until you get to "Change a Previous Massachusetts Return".
• You will be asked, "Do you want to change a previously filed Massachusetts return".
• If this is the state you want to amend click yes.
• The next screen asks you to read the Massachusetts Amend Instructions.  This is important as Massachusetts has changed their amended return and related instructions.

At this point, you can go on through and answer all of the questions.

You will need to print your amended return, sign it, and file by mail.  The amended return will be on your Form 1, with the Amended return block marked.  Please see the screenshot below.