The third stimulus can be based on a 2019 return if a 2020 return has not yet been filed when the IRS decides to issue a 3rd stimulus check.. But amending a 2019 return will not yield a stimulus check for your parents. It would take about six months to process an amended 2019 return. If they file a 2020 return and are eligible to receive the stimulus based on their 2020 return, they will get it after they file the 2020 return. And..again...there is not a place to request it, "claim" it, or enter anything about it on the 2020 return. It will be issued if their 2020 income qualifies them to receive it.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
