Retirement tax questions

Thank you. I figured there was no easy way to capture this in 2021 and I’d have to amend 2020 and you’ve confirmed that. Super annoying because I was communicating with the payroll company about this immediately in March 2021 and they assured me they were refunding it. Then as time  went by and I didn’t get it and followed up, I got the runaround until finally escalating it and being told the employees I had been speaking to at their company were misinformed and would be retrained to ask for the w2s or prove the excess prior to April 15th. Had they been knowledgeable I would have been saved a lot of time, aggravation, and now additional tax and penalty.