Hi, back in 2021 in filed my taxes and I didn’t do the Recovery Rebate Credit and I was just wondering how to do that on line?

Many people did not need to use the recovery rebate credit for 2021 because they had already received the 3rd EIP payment automatically.   If you already received it you cannot get it again.

TurboTax does not know who will receive the stimulus checks that the IRS is sending.   The IRS has identified some people who were eligible for the 3rd EIP payment who did not receive it and did not use the recovery rebate credit on their 2021 tax returns, so the IRS is sending out those payments.   You should check your online account with the IRS---many people received the 3rd stimulus before they filed their 2021 return, so they did not need to use the credit on their tax return.

Look at your online account with the IRS to see if they sent you $1400 in 2021.

https://www.irs.gov/payments/your-online-account

If you could be claimed as someone else's dependent in 2021, you are not eligible for the payment.

If you were eligible and do not receive a payment soon from the IRS, the other way to get the payment is to amend your 2021 return to use the recovery rebate credit before April 15, 2025.   If you did not file a 2021 return at all, then prepare one and mail it in.

If you need to amend:

https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-already-filed/L4VjJ9BA2_US_en_US?uid=m76mq6z2 

Do not expect quick results from amending. It can take four months or more for the IRS to process an amended return.  

You can watch for information here:

https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1