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Determining taxable amount for box 2a on CSA 1099-R

Working on taxes for my Grandfather who only has a government pension and social security for income.  I have a CSA 1099-R and am not sure what the taxable amount should be.  It currently says "unknown".  Box 1: 39576.  Box 2: Unknown.  Box 5: None.  Box 7: 7-Nondisability.  Box 9: 28281.  Should the taxable amount for 2a be the amount in box 1 or should it be box 1 minus box 9b?

    I have done taxes professionally for five years and this is a conundrum. What you can do is logon the Office of Personnel WEB site at On this .pdf document, go to page 3 and click on Issue 6 “How do I calculate the tax-free portion of my annuity which involves my retirement contributions?” A quicker way would be to logon to the OPM “Tax-Free Portion of Your Retirement,” at


      If it says UNKNOWN, leave that box blank, then answer the Interview questions.
      • I left the box blank and answered the questions and it seems to be giving him back the money he paid in federal tax throughout the year.  Is it possible that his taxable amount is $0?
      • I am working on my mother's return and am having the same problem.  Box 2a: Unknown.  When I put this into the 1040 and answer the questions the amount appears to be tax exempt and the refund amount is increased by the amount of taxes paid during the year.  I don't believe this is correct but need to know for sure.  I'm sure my mother would like to get that nice return.
      • I am working on my grandparents return.  My grandfather gets a pension every year and box 2a is "unknown".  Not sure what to put in turbotax for this.  Do I leave it blank or do I need to calculate it?
      I agree with younger daughter, however the instruction also say that you can use the general rule if you cannot use the Three-Year rule but it doesn't tell you what would prevent you from using the three year rule.  This is so confusing.  I have done my uncle's taxes both ways, using the amount from box 1 in 2a and leaving box 2a blank.  this is really confusing and I would love for a tax expert from the IRS or Turbotax to chime in because we are all guessing on this one.


        This is what I found.  If you retired prior to 1986 you probably had to report your annuity using the Three-Year Rule.  Under this rule, you excluded all the annuity payments from income until you fully recoverd your cost.  After your cost was recovered, all payments became fully taxable.  My father retired in 1975 so, according to this he has fully recovered his cost.  Therefore, box 2a would be the full amount of box 1.  Or, am I missing something?
        • "youngest daughter"'s comment makes the most sense.  But if it's that simple, I don't know why OPM wouldn't just enter the amount in box 2a instead of the word UNKNOWN.  My husband started drawing his pension this year and his is a whole different 1099R with more boxes on it. And his says Box 1= $x and Box 2a = $x.  For me this makes a difference of a couple thousand dollars, so it would be nice to be sure.
          Thanks for all your answers!
        • having same problem with TT program which apparently is not designed to deal with this, based on # of questions on this issue.  If left blank, this seems to tell TT none is taxable.  As the interview proceeds, a later question asks to "Describe the Taxable Amount", and this section assumes a number is entered.  So, even if, in this section, you check the dot that states all is taxable, because you left box blank when you entered the CSA 1099 R info, TT says that all of the blank (or zero) is taxable and enters that zero on 16b of 1040.  This seems to be what is happening.  I tried to not leave the box blank, and to enter the amount from 1 - gross distribution, but the same happens - TT shows the amount as not taxable, which still seems wrong to me.I

          I agree with other posters that this doesn't make sense, which makes people who are really thinking about this to question if this "unknown" income is truly not taxable.  "Youngest Daughter" seems to be the only one who's done useful research to get info about pre-86 retirees - thanks for that.  I still cannot figure out how to get the amount to show as fully taxable.  some background on my case:  Uncle deceased 4/2011, 1. gross dist 8,644,  2. unknown,  5. emp contrib 737,  7 distrib code 7-nondisability,  9b total emp contrb 11,267.  retired CSRS 1978.
        Refer to IRS Publication 721.  If the Simplified Method is to be used there is a worksheet that will allow you to calculate the taxable amount to enter as long as box 9b is not blank.
        • I wish a TAX EXPERT would answer this.  I am reduced to tears after reading various publications that just get more and more convoluted about using the "Simplified Method" (yeah, right) and deducting a portion of your contributions in box 5 from your gross distribution in box 1.   It does appear that if you answer the TurboTax interview questions honestly about that word "UNKNOWN" in box 2a, it is going to count the whole amount as untaxable.  I don't believe that's right, and can't decide whether to turn in this return and wait to be audited.  It's actually freaking me out.  I've spent 5 hours trying different tax programs this morning and I like Turbotax best, but geez, I'm uncomfortable with this.
        • I join the club.  I tried to read pub 721, 939, 1040, turbo tax instructions and more.  Nothing should be this difficult - why should we be expected to know more than OPM?  Most IRS instruction refer to simplified vs 3 year rule.  Fillable forPdf on-line form filler m for simplified after 1986 or 1996 starting date to determine taxable amount. Fillable Online apps irs Fillable Simplified Method Worksheet—Lines 16a and 16b - - apps Fax Email Print   - cut and paste the link - warning - made my head hurt.
        • It's June 2013 and this is still an unresolved issue with TT.