Merritt Personal Lines Manual: Special rules for insurance premiums.

Generally, you cannot treat insurance premiums as qualified medical expenses for HSAs. You can, however, treat premiums for long-term care coverage, health care coverage while you receive unemployment benefits, or health care continuation coverage required under any federal law as qualified medical expenses for HSAs. If you are age 65 or older, you can treat insurance premiums (other than premiums for a Medicare supplemental policy, such as Medigap) as qualified medical expenses for HSAs.

The premiums for long-term care coverage that you can treat as qualified medical expenses are subject to limits based on age and are adjusted annually. See Limit on long-term care premiums you can deduct in the instructions for Schedule A (Form 1040).