2015-2019 will have no effect on the 2020 stimulus.
The stimulus (1st and 2nd) was, and is, actually a 2020 stimulus, but because payments were issued before 2020 income and tax returns were filed, an *advance* payment was issued based on either the 2018 or 2019 tax returns already filed.
Now that it is 2021 and 2020 income is known and 2020 tax returns are actually filed, the IRS will not longer use the 2018 or 2019 tax returns.
If you have not already received all of either stimulus then the 2020 tax return has a question asking how much stimulus has been received and if an additional payment is due then it will be added to the 2020 1040 form line 30 and will be added to your 2020 refund.
(Amending or filing a 2018 or 2019 tax return to get the stimulus will be useless now.)
NOTE: the IRS will start accepting 2020 tax returns on Feb 12, 2021.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
