When unexpected health issues arise, having the support of a reliable insurance company on your side can reduce the stress and burden of medical bills. But insurance companies are notoriously changeable when it comes to what they will and will not cover, and many people have a limited understanding of those restrictions until it’s too late. Every year, Americans find themselves embroiled in battles over insurance coverage, making dozens of phone calls with bills for thousands in their hands.

Why is it so difficult to ensure proper coverage of medical issues? One of the biggest reasons is that some areas of coverage are subjective, not guaranteed. A stint in rehab following a long hospital stay may be abruptly cut off if the insurance company does not deem it necessary, and they never see the patient firsthand to make that determination. While Medicare coverage is extremely helpful in ensuring that older Americans have as much coverage as possible for hospitalization, there are many areas that benefit from additional supplemental plans—all of which add up to more out-of-pocket expenses.

Miriam Sheline is an attorney in Ohio, whose firm deals with thousands of medical-related debt calls every year, highlighting a real problem between the public and insurance providers.

“It’s a matter of seniors, when they start enrolling in Medicare, to really understand what their insurance covers and who they need to talk to at each state.”

Like anything else, an ounce of prevention is the best way to go when it comes to your healthcare coverage. As we grow older, preventative checkups and testing become more common, so even if you are in good health you can count on needing more coverage than when you were younger. Here are some tips for heading off potential problems.

Understand your coverage – Medicare is not a catch-all. There are still many costs associated with Medicare coverage, and taking the most basic plan can end up costing you a lot more if you end up with an illness or injury that comes with a hospital and rehab stay. Take the time to research your Medicare coverage and what, if any, additional insurance you may need.

Consider a supplement – If you are enrolled in Medicare, Medigap supplemental plans can be a very smart option to save you from costly copayments. Plans such as AARP Medicare Supplement offer coverage of inpatient coinsurance days, copayments, and deductibles. There are many private options for Medigap plans so you can choose one to fit your needs and your budget.

Document everything – If you find yourself facing a medical procedure, contact your provider and play the devil’s advocate. Find out what your coverage is for the best and worst-case scenario. Even a routine procedure has risks, so find out what you are covered for from the hospital stay and beyond (either home care or if you need to go to a skilled nursing facility for rehab). Document all of your communication with the insurance company and have a written outline of your coverage. Always note the date and time you called and the representative you spoke to—this will be a huge help if you find yourself fighting for reimbursement later.