You made it a bit complicated -- usually a bad idea in any situation. Here is what I would do:
1. Report to supervisor first. That debt is the responsibility of the company, it is the company that owes the town, not you.
2. That company debt originated from your ignorance at your job -- you made this debt to your company, whatever penalty you have to take is a matter between you and your company, nothing to do with the town.
3. The process that is appropriate seems like: the company pays this sum to the town (no matter in which way it was generated), then the company may or may not give you a penalty, say have you reimburse the payment the company made, plus reducing your salary.