It did happened to me when I have the job and didn't tell the SSI anything, they caught me through the IRS and took about 50 to 70 dollars off my SSI check every month since I no longer work and it was hard time for me.
For your situation, I hate to call the SSI because most of the time it took so long for me to just ask something and when I get in touch, they made mistake. I prefer to walk in to ensure that it goes straight, also when I walk in, there are no mistakes that I found since I have the SSI.
That's all I can say, just my advice
