"Back pay" is pay you receive in one payment for actual employment performed at an earlier time. Back pay under statute is payment that is required by law, such as the National Labor Relations Act, the Fair Labor Standards Act, and other Federal and State laws. The purpose of back pay is to create an employment relationship or to protect employees' rights to receive wages. Back pay, except penalties, interest, or legal expenses is considered "wages" if paid to the wage earner pursuant to a statute and is considered wages if it is paid to the wage earner for covered employment. For Social Security purposes, back pay will may be assigned or credited to the periods in which it should have been paid. Back pay not under a statute is still considered wages by the Social Security if it is extra pay for past employment. Back pay not under a statute will not assigned to any period other than the period in which it is paid.