Can I amend a TT 2016 return to correct income received per 1099R? 2020, I just had to pay $9100 pension $$ over payment I received. I want to adjust 2016 income.

[Shapnup]

The Gov't Pension fund will not issue me a corrected 1099R, but I do have their documentation supporting the over payment and validating my reimbursement.

[dmertz]

No, you cannot amend your 2016 tax return to claim a refund for this.  You must claim the repayment as a claim of right on the tax return for the year in which you made the repayment.  See "Repayments" in IRS Pub 17:

https://www.irs.gov/publications/p17#en_US_2019_publink1000172015