Social Security 2100 Act

Amends title II (Old Age, Survivors and Disability Insurance) (OASDI) of the Social Security Act (SSAct) to:

• increase the primary insurance amount formula factor from 90% to 93% for all eligible beneficiaries, beginning in 2016;
• revise computation of cost-of-living adjustments to use the Consumer Price Index for Elderly Consumers;
• increase the special minimum primary insurance amount for lifetime low earners based on years in the workforce.

Amends the Internal Revenue Code (IRC) to increase the gross income threshold for taxation of Social Security benefits from $25,000 to $50,000 for single taxpayers and from $32,000 to $100,000 for married taxpayers filing joint returns, beginning in 2016.

Amends the IRC and SSAct title II to impose the employment tax on all wage income above $400,000, effective in 2016. Requires incremental increases, up to 15.3% in 2084, in the employment and self-employment taxes.

Amends SSAct title II to include 2% of an individual's excess average indexed monthly earnings (over $400,000 per annum) in the formula for determining primary insurance amounts.

Amends IRC to increase the Social Security tax rate on employees and employers and with respect to self-employment income.

Requires reallocation of a portion of employment tax revenues from the OASDI Trust Fund to the Federal Disability Insurance Trust Fund for wages paid after 2014.