When an Infringement Notice is issued by an enforcement agency, you must pay it by the due date or do something about it.
If you don't do anything, it will become a Penalty Reminder Notice. The cost of the fine will go up.
If you still don't do anything about the fine, it becomes a Notice of Final Demand, and the cost of the fine goes up again.
If you still don't do anything about the fine:
Learn more about what's likely to happen next if you ignore your fine.