For the Earnings Test, there is a limit to the amount of income that can be earned if you’re under Full Retirement Age (FRA). The limits for 2012 were recently released:
For years in which the recipient of Social Security retirement benefits is younger than FRA, Social Security benefits will be reduced by $1 for every $2 greater than $14,640, or $1,220 per month.
For the year in which the recipient reaches FRA (but prior to reaching FRA), Social Security retirement benefits will be reduced by $1 for every $3 over the limit of $38,880 or $3,240 per month.
After reaching FRA, there is no limit on earnings.