No, the IRS will only use information from a 2018 return if you have not filed a 2019 return. For anyone who has already filed their for the 2019 tax year, there’s no turning back — the Internal Revenue Service will use your most recent tax return to calculate your stimulus check amount.
The IRS is going to setup a portal around April 17th, to allow taxpayers to enter their banking information. You would have to keep checking the IRS website for information.
https://www.irs.gov/newsroom/economic-impact-payments-what-you-need-to-know
