Senior Citizens Income Security Act of 2011

Senior Citizens Income Security Act of 2011 - Amends the Internal Revenue Code to: (1) to replace the formula for including social security benefits in gross income for income tax purposes with the formula in existence prior to the enactment of the Omnibus Budget Reconciliation Act of 1993; (2) eliminate mandatory withdrawals from retirement accounts after age 70-1/2; (3) eliminate employment taxes on individuals receiving social security retirement and Medicare benefits; and (4) allow an exclusion from gross income, up to $250 ($500 for joint returns), for dividends, interest, and capital gains. Appropriates additional amounts to the Hospital Insurance Trust Fund to compensate for losses in revenue resulting from the revision of the formula for including social security benefits in gross income.

Amends title II (Old-Age, Survivors, and Disability Insurance Benefits) of the Social Security Act to require the Secretary of Health and Human Services (HHS) to establish a procedure for allowing Medicare beneficiaries to waive Medicare entitlements and be automatically enrolled in the Medicare Alternative Voucher Program established by this Act.

Requires the authority of the Department of the Treasury to pay the principal and interest on debt held by the public, and the authority of the Commissioner of Social Security to pay monthly old-age, survivors', and disability insurance benefits under title II of the Social Security Act, to take priority over all other obligations incurred by the government in the event the federal debt reaches the statutory limit.