Can I add my 1098-T from previous years on this years tax return?

No. Report each form for the year it was issued. 

No.  If you did not use a 1098T on the return for year in which the 1098T is for, you can amend the tax return for that year in order to enter it.  You cannot put past year tax documents on your current tax return.

No, but you can amend last years taxes to add your 1098-T which may increase your refund, or lower your tax due, if applicable. Only report 2022 1098-T, not the 2021 one. You may have foregone credits for last years taxes 2021 due in 2022 or refunded in 2022. You can still amend.

You may need to do this for 2021 taxes that were due last year, you would need the software for 2021 to do this.

If you want to make changes or add a document to a tax return that has already been submitted, you should follow these guidelines. 

• You must first wait until the initial return is completely processed. 
• You will have to use the same TurboTax account that you used for the original tax return. 
• Once you begin your amendment, you'll see your original return.  
• The refund calculator will start new at $0 and only reflect the changes in the refund or tax due 
• Only make changes to the areas of your return that need amending. 
• You have three years from the date you filed your return or two years after you paid the tax due (whichever is later) to file an amendment 

Usually if your income is below 80,000-90,000 for the year of single filing status or between 160-180k for Married Filing Jointly, it may be helpful to add the deductions or credits if Box 5 is less than Box 1, especially. You can always enter your qualified and non-qualified expenses to calculate your maximum education credit.

@keiwan64