You are confused. The IRS did not go backwards and look to see if you were a dependent for 2019 when they processed your 2020 tax return. If they disallowed the credit on your 2020 return they did so for some other reason. Information from 2019 tax returns is NOT being used to determine your eligibility to get the recovery rebate credit on a 2020 tax return.
Amending your 2019 return will have no effect whatsoever.
So when the IRS processed your 2020 return that had $1800 on line 30 of the Form 1040, they reduced your refund and did not allow the $1800? Does the IRS believe you already received the first two payments? Check your account with the IRS to see.
https://www.irs.gov/payments/view-your-tax-account
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
