The IRS is only issuing the $600 second payment until January 15. You may receive a check, in which case you can check the IRS website to see when it is issued. (it may take a while to be delivered, of course.) If no check is issued to you by January 15, you will claim the rebate on your 2020 tax return. The IRS has released a draft version of form 1040 to include the second stimulus payment as well as the first stimulus payment. It will probably take a couple of weeks for that to be fully implemented in TurboTax, so don’t be in a hurry to file this year.