https://www.socialsecurity.gov/ssi/spotlights/spot-reporting-earnings.htm
http://www.socialsecurity.gov/ssi/spotlights/spot-medicaid.htm
The first $65 in gross earnings is excluded from income. If the $20 general exclusion is not yet used, it is also applied. After than, for every $2 you earn(before taxes), $1 is countable for SSI. If your income is low enough to still allow payment, then SSI goes down two months after the month of receipt and does not got up until 2 months after wages have stopped. If you do not have significant medical improvement, Medicaid and special SSI status continues even if your income is too high. If you have medical improvement, entitlement can stop whether you are working or not.
Examples:
An SSI only recipient starts working in July. Earns $1085 July, August, September. Stops work in September. Net wages after income taxes and FICA taxes may be about $900.
Countable wages $1085 minus $65 minus $20 divided by 2 is $500. The $500 countable wages from July through September will reduce SSI by that amount in September through November.
So, for July and August, the worker has an extra $900 to spend over the SSI payment. In September, the worker has a reduction in SSI of $500 but $900 from wages. The crunch could come in October and November when SSI goes down based on the income from August and September if that money is long gone and spent. But overall, the SSI recipient has $1200 more money in their pocket than they would have if they didn't work. The longer the person works and the more money they earn, the more money in their pocket. And also has the possiblity to continue this for a long time and possibly even fully back in to the workforce.
Special SSI status referenced above is for people who still need and use Medicaid. They have to continue to meet all other factors of SSI eligiblity including limited resources, and have to report their income and changes in living arrangements, but Medicaid can continue.
None of this sounds like cancelling benefits if you go to work.
