National Insurance number
The National Insurance number is a number used in the United Kingdom in the administration of the National Insurance or social security system. It is also used for some purposes in the UK tax system. The number is described by the United Kingdom government as a "personal account number".
Social Security (United States)
Both "defined benefit" and "defined contribution" private pension plans are governed by the Employee Retirement Income Security Act (ERISA), which requires employers to provide minimum levels of funding to support "defined benefits" pensions. The purpose is to protect the workers from corporate mismanagement and outright bankruptcy, although in practice many private pension funds have fallen short in recent years. In terms of financial structure, the current Social Security system is analogous to an underfunded "defined benefit" pension ("underfunded" meaning not that it is in trouble, but that its savings are not enough to pay future benefits without collecting future tax revenues).