SSI is Supplemental Security Income. SSI is not reported on a tax return.
Social Security Retirement/Disability/Survivors benefits are reported on a form SSA-1099 and the benefits received are reported on a federal tax return. The benefits may be taxable depending on the amount of other income you have entered on your tax return.
However, if the Social Security benefits are the Only income to be reported on the tax return, then there is no reason or need to file a tax return.
If you receive Social Security benefits, see this US Treasury website - https://home.treasury.gov/news/press-releases/sm967
