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

My hours change every week at my new part-time job and I am afraid of reporting wrongly. Any experience at all would help. The form asks for gross earnings, which I do not see until later. Who can I ask without risking my claim?

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.

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