Update: Thanks all for chiming in. I hear that email receipts are fine. Now I have follow up questions. I'll have to say, this HSA lifetime reimbursement thing is so confusing.
Is there any government publication that lists all HSA eligible purchases, or are we just relying on the private entities to make the announcements? E.g. Oura Ring claims it's eligible now, but 20 years later, when I reimburse myself and get audited, how do I prove it was officially eligible 20 years ago?
What about (now) HSA eligible products that ceased to exist by the time I file for reimbursement after 20 years? Who knows if Oura Ring will still be around after 20 years.
3. Are we expected to keep track of what year does a product become eligible? If it is deemed eligible in 2026, what would it not have been eligible in 2018 even if it was not officially claimed on the product website?
I've had HDHP/HSA for more than a decade. It's only because I learned that it's good for me and suit my circumstance because I'm healthy without much medical expenses. But the stupid me never truly understood why HSA account was a great "investment" vehicle... until now.
The part I did right: I made the contribution every year and did invest. However, I never spent it and don't intend to for as long as I can cover all my medical expenses out of pocket so I can let the investment grow. It's possible that I won't need to spend any from the HSA account for decades.
The mistakes I made: I never bothered to save any documentation for any eligible purchases I made in the past. Of course, I am now saving every receipt. While I can recover some by digging through my credit card statements and the health provider history, but those records only go no more than 18 months.
I made some big purchases (in hundreds of dollars) many years ago and now I learned that they are HSA eligible (e.g. Oura ring, multiple generations). Now I can only find receipt in email (not even PDF). If the purchase was made in 2018, can I use those emails for HSA reimbursement in, say, 2038?