You may understand the basics of how an HSA works. The fundamental premise is not so complicated. If you have a qualifying high deductible health plan you may contribute to an HSA. Then, you can take tax-free distributions to pay for qualified medical expenses. Sometimes, those payments come in the form of a reimbursement. Other times you can pay for the medical expense right at the point of sale. You may not know, however, about some unexpected times when a tax-free distribution from your HSA may be possible.