If you do not report some form of taxable income, credits, or income tax paid, your return may be rejected by the IRS.  Generally, one of these must be significant for your return to be accepted.  If none of these is reported, it may be the case that you are not required to file an income tax return for this tax year.  For more information or to determine if you are required to file a return, please reference the IRS Form 1040 Instructions.

If the only income that you had was from Social Security benefits, most likely these benefits are not considered taxable income.