Social Security has special rules called "work incentives" that help you keep your cash benefits and Medicare while you test your ability to work. For example, there is a trial work period during which you can receive full benefits regardless of how much you earn, as long as you report your work activity and continue to have a disabling impairment. 

The trial work period continues until you accumulate nine months (not necessarily consecutive) in which you perform what the Social Security Administration calls  "services" within a rolling 60-month period. Social Security considers your work to be "services" if you earn more than $640 a month in 2007.  For 2006, this amount was $620.  After the trial work period ends, your benefits will stop for months your earnings are at a level Social Security considers "substantial," currently $900 in 2007. For 2006, this amount was $860.  Different amounts apply to people who are disabled because of blindness.

For an additional 36 months after completing the trial work period, Social Security can start your benefits again if your earnings fall below the "substantial" level and you continue to have a disabling impairment. For more information about work incentives, the Social Security Administration recommends that you read the leaflet, Working While Disabled-How The Social Security Administration Can Help (Social Security Administration Publication Number 05-10095).