After you file

Could they have thought that my payment was an estimated prepayment for next year since the voucher I sent with it was actually a prepayment voucher, rather than for my current tax owed? And those forms they are requesting are related to a prepayment? I just have no idea what they are wanting from me, or how to go about finding out. The payment I sent was applied to my current taxes owed for 2020.

I tried calling them previously to verify the payment dates and never got through to a human being, so I’m hesitant to spend an hour trying again tomorrow.