NO. You do not do any such calculations. You simply enter the 1099R exactly as it appears and the software does all of the calculations.
@ hero2
wrote: "1099R from federal agency showing UNKNOWN in blk 2a when prior years showed an amount."
I'm not sure why you made a point to say "federal agency." As you go through the 1099-R interview, be sure you indicate the correct "type" of 1099-R. The questions and entry fields are different, depending on the type. Here are 4 types:
Regular 1099-R
CSA 1099-R
CSF 1099-R
RRB 1099-R
OPM texted me that I need to use the simplified general method to calculate the taxable portion of my pension. I was fortunate to have saved my original retirement packet which shows a specific amount of monthly payment as tax-free. I used this data to calculate my remaining tax-free contribution for my pension for 2023. Turbotax also used this method to calculate the tax free portion however, it did not calculate it correctly. Hereafter, all my pension will be 100% taxable since I used all my retirement contribution since I retired over 20 years ago.
Thank you all for your comments/suggestions to my inquiry.