If box 2a states unknown can you deduct employee contributions box 5 from the gross distribution box 1 to get the taxable amount?

We need more information. What kind of retirement income or plan is this, and why do you have taxable contributions?  What codes are in box 7?

This is my wifes retirement plan, its a CSA 1099r annuity paid. Box 7 has code 3 in it.  But the summary of payments YTD is different than the 1099R box 1. We tried calling OPM no luck.

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@grizzledwayn wrote:

This is my wifes retirement plan, its a CSA 1099r annuity paid. Box 7 has code 3 in it.  But the summary of payments YTD is different than the 1099R box 1. We tried calling OPM no luck.

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I believe you are correct about subtracting box 5 from box 1.  However, I am also concerned that the box 1 (gross payout) does not match what you actually received.  Someone else may have more experience with civil service pensions.  @dmertz 

thank you. I don't know what to do, if I use what they say was distributed we would owe an outrageous amount. But I don't know how to fix any of this. Thanks again for your help

It does seem odd that they would not know the amount to put in box 2a if they knew the amount to put in box 5.