The stimulus checks are an advance on a credit you can receive on your 2020 tax return. If something went wrong or you did not get the correct amount of stimulus payments this year, you can get it when you file your 2020 return in early 2021—if you are eligible. It will end up on line 30 of your 2020 Form 1040.
https://www.irs.gov/newsroom/economic-impact-payment-information-center-topic-j-reconciling-on-your-...
https://www.irs.gov/coronavirus/coronavirus-tax-relief-and-economic-impact-payments-for-individuals-...
https://ttlc.intuit.com/community/tax-topics/help/how-will-the-stimulus-package-impact-me/00/1393859
At this point, we do not know yet how long the new stimulus bill will delay the filing season due to changes to the 2020 Form 1040, software programming, software updates, etc., etc. Do NOT be in a hurry to file your 2020 tax return until more is known. Give some extra time to the IRS and the software programmers so that the software can handle the new 2nd stimulus, so that you can get it all by filing ONE time. It is never a good idea to file early, and it would be especially foolish to file an early 2020 return.
