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".
Pension
Many countries offer state-sponsored retirement benefits, beyond those provided by employers, which are funded by payroll or other taxes. In the United States, the Social Security system is similar in function to a defined benefit pension arrangement, albeit one that is constructed differently from a pension offered by a private employer; however, Social Security is distinct in that there is no legally guaranteed level of benefits derived from the amount paid into the program.