Most of us know that an individual enrolled in Medicare Part A or B isn't eligible to contribute to a health savings account. This can create a problem for employees who work beyond their 65^th birthday, which seems to be the norm these days.

If the employee chooses to stay on his company's health insurance, and if the only benefit option is a high deductible health plan, he can have the health coverage but will not be able to pay for his out-of-pocket expenses with pre-tax dollars through an HSA – unless, of course, he already has an HSA; he can continue to spend his existing HSA funds but cannot contribute additional money to the account.

So why would somebody who's eligible for Medicare remain on his company's health plan? Couldn't he just purchase a Medicare supplement or sign up for a Medicare Advantage Plan instead? It's an option, but a lot of employees choose to keep their employer-sponsored coverage because they're also covering a younger spouse who's not yet Medicare-eligible.