If you are required to turn in a tax transcript, it must be entire transcript with both federal and state taxes and include a wet signature, which means signed by hand. If you signed electronically when you submitted your taxes, you must print out the signature portion of the transcript, sign it by hand, and scan it before uploading. Typically, a tax transcript is more than 50 pages.
If you were not required to file taxes for a year, you will need the transcript from the IRS that confirms that you were not required to file.
Tax documentation is commonly requested for verification and special circumstance appeals.