Checking my last day of health coverage - any advice?

I was told my coverage ends on my last day, but the letter says the end of the month. I have been trying to stay organised about it. I do not want to be surprised by a bill. What should I do about appointments?

Ask HR to confirm the exact date in writing. I also called the insurance company to double-check.

I moved my appointments earlier while coverage was active. It saved me a bill.