What documents do I need to attach when I mail to state tax return?

Generally, the only documents you need to attach to the state return are those documents that show state income tax withheld.

• If your W-2 has an amount in Box 17, attach it.
• If your 1099-INT doesn't have an amount in box 17, don't attach it. 
• If your 1099-DIV doesn't have an amount in box 16, don't attach it. 

That's very helpful! Thank you!

What documents do I need to attach when I mail to state tax return?

What Helen said above is still true. Attach those forms which have state withholding.

On the other hand, each state has their own instructions for what to attach.

Please tell us what state you are talking about, and if you are planning to file by mail. Normally, with e-file, you let TurboTax attach whatever is required.

I am filing in Iowa and mailing in my return. What IRS forms should I attach?

Any income documents, such as W-2's, and 1099's of any kind should be attached  to your mailed state return.  The Filing Instructions for your state return gives more info.

Normally, any pages that printed after your state filing instructions need to be included.

@Michelle154 

I can't find anything in the instructions. I think I will just attach the entire IRS return with all of the forms. I would rather attach too much than not enough. 

It probably isn't necessary to attach the federal return, but it won't hurt any either.

@Michelle154