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)
To calculate the total benefits a retiree is eligible for, the average indexed monthly salary (AIME) is then divided into three separate salary brackets—each multiplied by a different benefit percentage. The benefits receivable (the so-called Primary Insurance Amount, PIA) are the sum of the salary in each bracket times the benefit percentages that apply to each bracket. The benefit percentages are set by Congress and so can easily change in the future. The "bendpoints", where the brackets change, are adjusted for inflation each year by Social Security. For example, in 2013 the first bracket runs from $1 to $791/month and is multiplied by the benefit percentage of 90%, the second salary bracket extends from $791 to $4,781/month is multiplied by 32%, the third salary bracket of more than $4,781/month is multiplied by 15%. Any higher incomes than the ceiling income are not FICA covered and are not considered in the benefits calculation or in determining the average indexed monthly salary, AIME. At full retirement age the projected retirement income amount (PIA) is the sum of these three brackets of income multiplied by the appropriate benefit percentages—90%, 32% and 15%. Unlike income tax brackets, the Social Security benefits are heavily biased towards lower salaried workers. Social Security has always been primarily a retirement, disability and spousal insurance policy for low wage workers and a very poor retirement plan for higher salaried workers who hopefully have a supplemental retirement plan unless they want to live on significantly less after retirement than they used to earn.