The CARES Act that was signed last week included the issuance of “economic impact payments” or stimulus checks to people who earn under a certain threshold. It previously required Social Security beneficiaries (who are not typically required to file tax returns) to file an abbreviated tax return to ensure that they would receive these payments.
It has since been amended to not require Social Security beneficiaries to file tax returns. Instead, Social Security recipients will receive these payments as a direct deposit or by paper check, just as they would normally receive their benefits. Note that this also applies to Railroad Retirement Board beneficiaries. See here for the press release from the Treasury: https://home.treasury.gov/news/press-releases/sm967