Should I enter the third stimulus amount for federal taxes? Is this amount taxable. If not, why am I entering the amount?

[xmasbaby0]

No it is not taxable.   Yes you have to enter  that you received it.   You should have letter 6475 that tells you how much you received.   If you do not enter that correctly then the software will put the stimulus on your refund again and your return will go under review.  You will be asked in Federal Review for the recovery rebate credit.   Answer correctly so that your refund will not be delayed.

[MayaD]

The third Stimulus is not taxable. 

You will need to enter the amount received to accurately calculate your Recovery Rebate Credit when you file your 2021 federal tax return.

People who didn't receive a third Economic Impact Payment or got less than the full amount, may be eligible to claim a Recovery Rebate Credit on their 2021 federal tax return.

[Opus 17]

If you qualify, it will automatically be added to your tax refund.  If you received the stimulus check, you have to tell Turbotax to take it back off your refund.  If not, the IRS will take it off anyway, and it will substantially delay payment of the rest of your refund.