Hot off the press ... straight from the horse's mouth ...

https://www.irs.gov/newsroom/treasury-and-irs-begin-delivering-second-round-of-economic-impact-payme...

Didn't get my personal second stimulus

check

Where is my first and second stimulus check

If you did not receive your first and/or second stimulus payment or if the amount received is not correct, you can claim it on your 2020 tax return as the Recovery Rebate Credit. 

In TurboTax Online, to claim the Recovery Rebate credit please do the following: 

1. Sign into your account and continue from where you left off 
2. Click on Federal in the left-hand column, then on Federal Review on the top of the screen 
3. On the next page titled Let's make sure you got the right stimulus amount, click on Continue 
4. Follow the interview 
5. TurboTax will determine whether you are entitled to any additional stimulus 
6. Any stimulus amount remaining due to you will show as a credit on line 30 of your form 1040. 

If you never received them (check/debit card or direct deposit) and you haven't filed your 2020 tax return you can add the missing payments to your return as a Recovery Rebate Credit.  After you enter your personal identification information and income and deductions you will arrive at a "Federal Review".  In that tab you will find the stimulus questions to indicate you did not receive any payments.  

If you filed your return already you can check line 30 of your form 1040 to verify the missing amount is there.  If it is not you will need to amend your return to claim the missing amounts.  

Sign in to your TurboTax account, select the "Amend" option and follow the prompts to complete the amendment.  You can click on the "Federal Review" tab to get to the stimulus questions.  

Here is a link with more information on the Recovery Rebate Credit.