Further clarification, this is for the state of Massachusetts.
This is an inherited IRA from a deceased parent that I have held for 9 years now and have been receiving RMDs on for those 9 years. I know what the 2021 RMD was based on the 1099-R that I received, but do I have to go back and sum up the RMDs for 2013-2020. for this line? I don't recall ever doing this before.
Yes, when TurboTax asks about the total distributions received in previous years then you will need to go through your records and add them up.
Massachusetts (MA) doesn't allow deductions of traditional IRA contributions so you will have to enter the contributions to the traditional IRA under contributions previously taxed by MA and enter distributions received so TurboTax can calculate what your basis is and how much is taxable. If you do not enter this information about the contributions and distributions then the whole distribution will be taxable in MA.
if you don't do it now, the amount you are paying tax on will be added later to the total distributions taxed that you are reluctant to research at this time.
Since I've been using TT for many years, it should KNOW this information and carry it forward-- if not, why not?