You can always file a tax return, although if your only income is SS, it is non-taxable and there is usually no benefit to filing a return.
To e-file, you must have at least $1 of taxable income. You can create $1 of taxable interest income. The IRS knows about this trick and it won't cause you any problems or to owe any tax. You can file a zero income return by mail if you like, although there is little reason to do so.
