Reporting part-time earnings while on benefits - what worked for you?

I work some days through a staffing agency while still certifying. The form asks for gross earnings, which I do not see until later. Did anyone get an overpayment notice from a mistake?

I estimated and then checked my pay stub. When there was a small difference I wrote to the agency to correct it.

Keep everything in writing and save the confirmation numbers. It saved me later.