Under what circumstances am I allowed to pay my international medical bill from my HSA?

Nomad

Dear Nomad

As long as the medical care is covered, you can be reimbursed from your Health Savings Account.  (See IRS Publication #502 for a list of covered medical items.)  Of course, you cannot claim HSA funds for something that your health insurance plan has paid for; some plans will cover emergency care in these situations.

For the HSA, it should not matter whether the medical care happened in the United States or elsewhere.   The only tricky thing might be the exchange rate between dollars and whatever currency the bill is rendered in.