If you're sure you are supposed to have an IP PIN but didn't receive one from the IRS in a letter at the end of December or in January, you should try to retrieve it.
Have you tried retrieving your current-year IP PIN at this IRS website tool?
If you are unable to retrieve the IP PIN online, you can phone the special IRS phone number shown on that page, and if they can identify you completely on the phone, they will postal mail the IP PIN to you within 21 days.
If you are supposed to have an IP PIN, you can't efile without it, or it will reject. It's possible to file on paper by printing, signing, dating, and mailing without the IP PIN, but it can take the IRS longer to process your return since it will require additional screening. To file by mail, one would make that choice in the FILE section, and it should prompt you to print the return. TurboTax does not mail it for you. If you go that route, you have to print, sign, date, and mail the return to the IRS address in the Filing Instructions which also print.
If you mail, it's a good idea to mail by a method that has tracking such as certified mail, priority mail, etc.
This Turbo Tax FAQ will provide more information on the IP PIN
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