I am on SS and still work so I file an income tax return every year. However, if you are on SS and have not been filing an income tax return, as some people don't, you will need to file a simple return in order to get your stimulus check, even though you don't owe any taxes. This includes Low-income taxpayers, senior citizens, Social Security recipients, some veterans and individuals with disabilities who are otherwise not required to file a tax return .This was posted yesterday on IRS website. They offer free software to file simple return for free.
I would post the link on here but seems like I get an infraction every time I post a link,but if you go their website and find Economic Impact Payments, Ir-2020-61 posted yesterday, you will see it