At age 65 and older, your funds continue to be available without federal taxes or state tax (for most states) for qualified medical expenses; for instance, you may use your HSA to pay certain insurance premiums, such as Medicare Parts A and B, Medicare HMO, or your share of retiree medical coverage offered by a former employer. 

Funds cannot be used tax-free to purchase Medigap or Medicare supplemental policies. If you use your funds for qualified medical expenses, the distributions from your account remain tax-free. If you use the monies for non-qualified expenses, the distribution becomes taxable, but exempt from the 20 percent penalty. 

With enrollment in Medicare, you are no longer eligible to contribute to your HSA. 

If you reach age 65 or become disabled, you may still contribute to your HSA if you have not enrolled in Medicare.