If you disagree, tell your caseworker right away that you want their decision in writing, and that you want an “administrative hearing”. This will let you fight (appeal) the agency’s decision. How to Fight an Overpayment of Cash Assistance or Medical Assistance has more on how to do this.
The agency might think you did not report income that you or a family member got. You might be able to show at the hearing, or at a pre-hearing conference, that you do not owe anything, or that you gave the agency the information, but the agency lost it.
You might be able to explain you did not give that information because you did not realize you had to. Or that the agency made wrong assumptions about your situation.
Example: An investigator sees someone else’s car parked outside your home. The investigator concludes that person is living with you. In fact, the car has broken down. Its owner just left it there.