Checking my last day of health coverage - first time posting

I was told my coverage ends on my last day, but the letter says the end of the month. This is my first time dealing with any of this. I do not want to be surprised by a bill. Did coverage match what HR said?

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

Thanks for writing this out. I went through something close to it 9 months ago, and it got easier once I kept a simple log of every call and form.