It depends.
If you have filed a tax return in 2018 or 2019, you do not need to do anything. The IRS will use the most updated information from your tax return.
If you have Social Security income and are not required to file a tax return, you do not need to do anything. The IRS will use the information used to deposit your Social Security payments.
If you have not filed a tax return for 2018 or 2019 because you did not have a filing requirement, you can use the link below to register for your stimulus tax payment.
Stimulus check registration
The following links can also be used for additional information.
What does the stimulus package mean for you?
TurboTax Corona Virus Tax Center Updates
IRS Coronavirus Tax Relief