When you work and pay social security taxes, you earn social security credits.
Most people earn the maximum of four credits per year.
Each of the three main Social Security programs accumulates credits in the same way. In future years, the amount of earnings needed for a credit will rise as earnings rise. The credits you earn will remain on your Social Security record even if you change jobs or have a period of no earnings. Self-employed individuals and military personnel earn credits in the same way as regular workers. However, special rules apply for certain types of work.