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 Administration
The United States Social Security Administration (SSA) is an independent agency of the U.S. federal government that administers Social Security, a social insurance program consisting of retirement, disability, and survivors' benefits. To qualify for most of these benefits, most workers pay Social Security taxes on their earnings; the claimant's benefits are based on the wage earner's contributions. Otherwise benefits such as Supplemental Security Income (SSI) are given based on need.