Got an overpayment notice, what now?, administrative assistant here

The agency says I reported earnings incorrectly, but I think I followed the instructions. The letter mentions an appeal window and a repayment plan.

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

If you are unsure, free legal aid in your area may help for this kind of notice.