Insurance agent Jo Ann Charron, left, talks with her administrative assistant Enedelia Morales during a meeting about details on a client's insurance coverage at the Benefits Dallas offices.(Photo: LM Otero, AP)

How many times have you gotten a medical bill for more than you were expecting? Chances are, it's happened before, and you're not the only one who's been shocked at the price tag on a service that your insurance should have covered. Here are five possible reasons why your insurance company didn't pay the entire bill.

1. Your insurance company made an error.

Anyone in the industry can tell you that insurance companies are notorious for inconsistent information, and this unfortunately applies to essentially every part of the insurance process. To protect yourself, get in the habit of documenting the date, time and call reference number every time you contact your insurance company. By doing so, if and when something occurs, you have the leverage to dispute your claim because it was ultimately the fault of representatives of the company. For example, if you call to verify that a provider is in your network, and you end up billed for out-of-network services, you'll be able to reference your original call and get your bill reduced.

If you have a question once you get your bill, always call your insurer to ask how the claim was processed and how the amount covered applied to the service. You will receive varied replies, but often, the person at the insurance company will catch a mistake and have it reprocessed.

2. Your provider "accepts your insurance" — but isn't in your plan's network.

Many people think that it is sufficient to verify that your doctor "accepts your insurance," but this doesn't mean you're totally covered. Many physicians will "accept your insurance," in that they will bill your insurance and accept payment, but this doesn't mean that the doctor is in your network. After your appointment, the doctor's office can "balance bill" you, meaning that you will be charged the difference between what was billed and what your insurance paid.

3. Your free annual examination wasn't billed as a free exam.

The Affordable Care Act mandates that annual exams be free — how can this possibly go wrong? Quite easily, it turns out. If you go to your doctor for your free exam but have something else done that isn't considered part of the free exam, the entire exam is billable. For example, if you go in for an annual exam and ask your doctor to look at your ear because you've had an earache, the exam can be billed as an examination with diagnosis, which is no longer free. Before asking for additional services during your free exam, check with your doctor that it won't be billed as an exam with diagnosis.

4. Your insurance company practices "bundling."

"Bundling" occurs when a secondary procedure is considered to be part of a primary procedure. Think of a carpel tunnel procedure: A surgeon will often consider the incision and the carpel tunnel procedure as separate charges. A problem arises, however, when the insurance company considers the incision as part of the carpel tunnel procedure and "bundles" the two charges. In this case, the insurance company will pay only for the carpel tunnel procedure, leaving you to pay for the incision.

Bundling cases are interesting, because sometimes, the doctor is correct, and sometimes, the insurance company is correct. These cases require research into the billing codes used, what occurred during the procedure, and the specialty's (i.e., orthopedics vs. cardiology) standard billing practices. If you have a complicated bundling issue that has lead to massive bills, you might consider hiring a medical billing advocate for professional help getting your bill resolved.

5. There's missing information.

Often, insurance companies will request additional information from the provider, and for whatever reason, the provider does not give the information or it gets lost in processing at the insurance company. If you are not diligent in following up when you receive an insurance statement indicating that nothing was paid, your claim may never be paid. These cases are easily remedied, but you — the patient — must follow up to ensure that the insurance company receives and processes the requested information.

NerdWallet Health is a USA TODAY content partner providing general news, commentary and coverage from around the Web. Its content is produced independently of USA TODAY.

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