Social Security for the 21st Century Act

Social Security for the 21st Century Act - Amends title II (Old Age, Survivors and Disability Insurance) (OASDI) of the Social Security Act (SSA) to add a new part B (Retirement Security Accounts) under which an eligible individual may elect to make retirement security account contributions to a retirement security account (RSA) established by the Commissioner of Social Security for each such elector in his or her name and maintained for his or her benefit.

Directs the Secretary of the Treasury to transfer from the Federal Old-Age and Survivors Insurance Trust fund for crediting by the Commissioner to an elector's RSA of a retirement security account contribution based on an applicable percentage of the elector's FICA (Federal Insurance Contributions Act) or self-employment taxes for investment according to the elector's designated investment options under a system similar to the Thrift Savings Plan for Federal employees, with a Retirement Security Fund (RSF) established in the Treasury that is to be managed by a Retirement Security Fund Investment Board (RSFIB). Provides for the treatment of RSA distributions and the off-budget budgetary treatment of RSF and its RSAs.

Requires RSFIB to study and report to the President and the Congress on increased investment options for electors.

Amends SSA title II to establish in the Treasury the Protect Social Security Account to save budget surpluses until a reform measure is enacted to ensure the long-term solvency of the social security trust funds. Requires the Secretary to: (1) pay into the Account at the end of each fiscal year in the FY 2000 through 2010 period an amount which in the aggregate, at the end of such period, will equal 70 percent of any such surplus projected by the Secretary for that period; and (2) invest all such amounts in public debt obligations.