Countless Americans rely on Social Security to pay the bills in retirement — perhaps a little too heavily. Though Social Security is only supposed to replace about 40% of the typical worker’s previous earnings, an estimated 21% of married beneficiaries and 43% of single beneficiaries aged 65 and over depend on those benefits to provide 90% or more of their retirement income. Worse yet, some seniors don’t get to keep those benefits in their entirety, because there are 13 states that tax Social Security income to varying degrees.