Sorry you can't efile 2021 through Turbo Tax. You have to print and mail it. Do you need to prepare 2021?
To do a prior year return you have to buy the Desktop program here,
https://turbotax.intuit.com/personal-taxes/past-years-products/2021
You will need a full Windows or Mac to install it on.
You might need to go to a local tax place or if you have a simple return and want to file for free you can fill out the forms by hand. Here are some basic forms…..
Here is the IRS 2021 Form 1040
https://www.irs.gov/pub/irs-prior/f1040--2021.pdf
or if you want bigger type use 1040SR for Seniors,
https://www.irs.gov/pub/irs-prior/f1040s--2021.pdf
And 2021 Instructions
https://www.irs.gov/pub/irs-prior/i1040gi--2021.pdf
2021 Tax and EIC Tables
https://www.irs.gov/pub/irs-prior/i1040tt--2021.pdf
Sch 1 : https://www.irs.gov/pub/irs-prior/f1040s1--2021.pdf
Sch 2 : https://www.irs.gov/pub/irs-prior/f1040s2--2021.pdf
Sch 3 : https://www.irs.gov/pub/irs-prior/f1040s3--2021.pdf
You have to print and mail prior year returns. When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS received the return. Don’t forget state.
