Your HSA funds can be used tax-free to pay for qualified medical expenses, even if the expenses are not covered by your HDHP. This includes expenses incurred by your family.
There are hundreds of qualified medical expenses, including many you might not expect: over-the-counter medications, dental visits, orthodontics, glasses, long-term care insurance premiums, cost of COBRA coverage, medical insurance premiums while receiving federal or state unemployment compensation, and post age-65 premiums for coverage other than Medigap or Medicare supplemental plans.
In addition, HSA funds may be used to pay your Medicare Parts A and B premiums and for employer-sponsored retiree plans. All of these expenses may be paid for with your HSA funds, free from federal taxes or state tax (for most states). Refer to IRS Publication 502 for a more complete list of qualified medical expenses.