Yes. It follows the plain text of the rules — the IRS explicitly permits reimbursing prior-year expenses, with no year limit stated.
Yes. It isn't a loophole, an aggressive interpretation, or a gray area — it's the rules working as written.
IRS Notice 2004-50, Q&A-39 states that a qualified medical expense incurred in a prior year may be reimbursed from an HSA, so long as the expense was incurred after the account was established and hasn't been reimbursed or deducted elsewhere. The guidance sets no limit on how many years may pass.
What makes people nervous is the size of the eventual withdrawal, not its legality. Reimbursing $60,000 of accumulated expenses in one year looks unusual on a return, even though every dollar is properly supported.
Which points at the real requirement: this is a documentation strategy first and an investment strategy second. Run it with organized, retrievable records showing provider, patient, date, service, and amount for every dollar, and it holds up. Run it out of a drawer and it doesn't.
This is general information, not tax advice. Talk to a CPA about your situation.