Strengthening Social Security Act of 2013 - Amends the Internal Revenue Code to prescribe special rules for the determination of taxable wages and self-employment income above the contribution and benefit base after 2013.

Amends SSA title II to include surplus average indexed monthly earnings (AIME) in the determination of primary OASDI amounts.

Directs the Bureau of Labor Statistics (BLS) of the Department of Labor to prepare and publish the Consumer Price Index for Elderly Consumers (CPI-EC) that indicates changes over time in expenditures for consumption which are typical for individuals in the United States who have attained early retirement age for purposes of an old-age, wife's, or husband's insurance benefit.

Amends title II (Old Age, Survivors and Disability Insurance) (OASDI) of the Social Security Act to make the CPI-EC the applicable Consumer Price Index (CPI) for computation of cost-of-living increases in OASDI benefits for such individuals.