How do I get a copy of my tax return to give the IRS?

This sounds a little fishy. The IRS doesn't usually ask for a complete copy of your tax return. Are you sure it's really the IRS and not a scammer or identity thief? How did they contact you - by phone, email, or a letter in the regular mail? Did you have any previous contact with the IRS about this tax return?

If it's a letter, what's the letter number or notice number at the top right, starting with LTR or CP? Where do they want you to send the copy of your tax return? You can call the IRS at 800-829-1040 (not the number in the letter) and ask them if they sent the letter.

If they contacted you by phone or email, it's a scam. The IRS doesn't initiate contact with taxpayers by phone or email.