Overpayment letter from the unemployment office after 14 years as a copywriter

The agency says I reported earnings incorrectly, but I think I followed the instructions. There are 14 people counting on me, so I am trying to be careful. The letter mentions an appeal window and a repayment plan. Are payment plans possible?

Collect your pay stubs and certification records for the weeks they name. Mine showed the error was a date mix-up.