how to file amendment for payback of relocation allowance from 3 yrs ago

Hello,

In 2020, my current employer offered and paid in advance of a relocation allowance that is great than $3000. With the Pandemic situation, my management agreed last year (2022) to let me continue work remotely.  As I did not relocate, Payroll is asking for the payback of this allowance....

I had reported and paid the tax in my 2020 Fed/CA filing and filed on time before April 2021.     Now, in 2023, Payroll said they will send me a letter of payback evidence for IRS after I they receive my one lumpsum payment and they will provide a letter for a backup document for IRS, but Payroll will not provide a revised 2020 W2.

 

Questions

- can I still file a 2020 Amendment some time in 2023?  Is it still within the 3 years limitation for filing amendments?

- since I won't get a 2020 W2-C from my employer (after I complete the payback in the next few months) and this allowance was taxed as my income in 2020,  where and how do I submit this allowance amount in my 2020 amendment filing?  Do I adjust the Box 1 of W2 entry in 2020 TurboTax amendment or as a deduction item somewhere?  (I used standard deduction in 2020 filing)

- Do I need to file an amendment for Fed and one for CA state in 2020?

- Do I also need to file amendments for 2021 and 2022 (for both Fed and State)? since the AGI from 2020 will be changed?

Thank you