Checking my last day of health coverage - what worked for you?

I was told my coverage ends on my last day, but the letter says the end of the month. I worked as a janitorial supervisor before this. I do not want to be surprised by a bill. How did you confirm your end date?

Thanks for writing this out. I went through something close to it 3 months ago, and it settled down once I kept a simple log of every call and form.