If you had no taxable earned income from work on your tax return of at least $2,500 then you are not eligible any tax credits that require earned income, such as the Child Tax Credit, the Other Dependent Credit or the Earned Income Tax credit.
If the Social Security benefits is the Only income to be reported on the tax return and there is no federal income taxes being withheld, then there is no reason or need to file a tax return..
Unless you also received a Form 1095-A for your health insurance through one of the State Marketplace Exchanges or from healthcare.gov then you must file a tax return.
