i am on SSI how much can i earn without it changing my monthly income

Earnings trigger a trial work periodDuring a trial work period, a beneficiary receiving Social Security disability benefits may test his or her ability to work and still be considered disabled. We do not consider services performed during the trial work period as showing that the disability has ended until services have been performed in at least 9 months (not necessarily consecutive) in a rolling 60-month period. In 2012, any month in which earnings exceed $720 is considered a month of services for an individual's trial work period. In 2013, this monthly amount $750.   http://www.ssa.gov/oact/cola/twp.html