Got an overpayment notice, what now?

The agency says I reported earnings incorrectly, but I think I followed the instructions. Any experience at all would help. I did not notice any errors at the time. Are payment plans possible?

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

Thanks for writing this out. I went through something close to it 13 months ago, and it settled down once I kept a simple log of every call and form.