If your 1099R Statement Box 2.a for the Taxable Amount is marked as 'Unknown'; this means that OPM did not calculate the tax-free portion of your annuity.
The most common reasons for not calculating the tax-free portion of your annuity:
Your case is a Disability Retirement
You retired prior to November 19, 1996
You have Voluntary Contributions, an apportionment was paid to your former spouse(s)
Your case has not been finalized and you are in Interim pay status
You have Survivor benefits payable and/or
Your case is an Office of Workers Compensation case.
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