This is similar to a question that was answered for me here awhile ago, but the situation is slightly different. Regarding Traditional IRAs If an Administrator is filing a few years of previously unfiled taxes for a decedent, and knows that the decedent did previously file 8606s but is unsure of the last 8606’s figures/basis and so is unsure of decedent’s basis in IRAs, can the Admin. opt not to file 8606 and to have the whole distribution taxed as if there were no basis without this causing issues w/IRS and or penalties? Also, the decedent had been taking required distributions for many years, and was well past the age for making contributions. Is there any reason in this scenario that IRS would require 8606? The Admin. is also the sole Estate beneficiary so no other beneficiaries would be upset about more of the possible inheritance being eaten up by taxes due to not filing 8606.