National Insurance number
The National Insurance number is used as a reference number in the Pay As You Earn system, and also by the self-employed. It is also used in applications for Individual Savings Accounts (ISAs), to check that an individual has opened only one ISA in a tax year.
Social Security (United States)
In the United States, Social Security is the commonly used term for the federal Old-Age, Survivors, and Disability Insurance (OASDI) program and is administered by the Social Security Administration. The original Social Security Act was signed into law by President Franklin Roosevelt in 1935, and the current version of the Act, as amended, encompasses several social welfare and social insurance programs.