It is a benefits reduction that can apply to those receiving Social Security retirement or survivors benefits and still earning income.
If you’re under full retirement age, $1 in benefits will be deducted for each $2 in earnings you have above an annual limit of $15,720 in 2015. In the year you reach your full retirement age, your benefits will be reduced $1 for every $3 you earn over a different annual limit of ($41,880 in 2015) until the month you reach full retirement age. These numbers increase slightly most years. There is no limit on your earnings starting with the month in which you reach full retirement age.
Only wages and net earnings from self-employment count toward the limits. Non-work income such as other government benefits, investment earnings, interest, pensions, annuities, and capital gains don’t count.