Thanks for such a fulsome response. Since you're so helpful, here's some additional details that, if you have time, I'd love for you to gut-check me on.
Yes, it was a general health care FSA. I used the QLE (the marriage) with the FSA to reduce this year's contribution amount to the exact amount that was in the account at that moment, essentially preventing any further contributions. I submitted receipts to bring the balance of the account down to $0. I then received an email from FSAFEDS on September 10 that said, "This email is to notify you of activity on your account: Your coverage was ended." I'm hoping that means the FSA was dead at that point?
The HDHP plan became effective September 15. The HSA was opened automatically, and the first contribution reached the HSA on September 30. I intend to max it out this year under the "last month" rule and keep the HDHP all next year.
So, given all that - am I still good, @BMcCalpin? Thanks again!
