Your tax return must include form 8606 any time you make a non-deductible IRA contribution, or make a withdrawal or conversion from an IRA that has a non-deductible basis. However, form 8606 is not generated for a year in which you neither make a non-deductible contribution or withdrawal.
Any year that you have a non-deductible contribution or withdrawal, you must enter the information from the most recent previous form 8606 and it will be combined with your current year information to generate a new form 8606. For example, if you made non-deductible contributions in 2019 and 2020 and 2022, but not 2021, your 2022 tax return would require information from your 2020 form 8606. Your tax program will carry this information forward, but you can also manually enter the information as long as you have a copy of your prior form. (Such as if you change tax software, change accountants, or have a data loss.)
When you make IRA withdrawals or conversions, including in retirement, your withdrawal or conversion is only partly non-taxable if you can prove you made previous non-deductible contributions and reported them correctly. Don't count on the IRS to keep track for you. For that reason, I would make sure to save copies of any form 8606 that you file for the rest of your life (yes, really), either paper copies or PDFs or something else. Form 8606 breaks the usual rule that you can discard tax papers after 3 or 7 years. You probably won't be audited, but if you are, you can be asked to prove that you made non-deductible contributions and reported them properly at the time.
(To clarify: To file a correct tax return, you only need the most recent prior 8606, so you at least need to save that tax return. However, in case of audit, you could be asked to show your past 8606s as well, to prove your numbers add up, so it would be a good idea to save them all.)
