Q. Can I add my 2021 1098-T form to my 2023 taxes?
A. No. You would have to amend your 2021 return to claim it. If you did not file a 2021 return, you can still file one. It cannot be e-filed. You will have to mail it.
What are you hoping to achieve? For most college age students, the parent claims the tuition credit ("files the1098-T") on their tax return, not the student. If some of a student's scholarship is taxable, the student may have to use the 1098-T, as well.
There's a new urban myth among college students that says they can get a $1000 from the government just for filing a tax form. For most of them, they simply aren't eligible. A full time unmarried student, under age 24, even if you don't qualify as a dependent, is only eligible for the refundable portion of the American Opportunity Credit if he supports himself by working. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. It is usually best if the parent claims that credit.
You cannot claim a credit if you are, or can be, claimed as a dependent by someone else.
Reference: Line 7 instructions for form 8863. https://www.irs.gov/instructions/i8863
