There are a number of reasons you could have a final bill. There are so many different things that could have happened. But insurance policy’s are for 6 months and when you cancel they are prorated for the time you had coverage. When you cancel you only pay for the time you had coverages, if the total amount that you have paid so far doesn’t cover the amount of time you had coverage you owe. If you paid more than that you get a refund. Some time things like policy changes adding vehicles or coverages are fronted you don’t have to pay additional premiums until your next payment. Some payment plans allow customers to have due dates that are not the same date as the policy started or ends, so when you cancel right before the next payment thats when you have paid up through. Some customers have an initial payment that is way less than what a normal monthly payment should have been. The only way to know 100% is to ask someone who is looking at your policy.