Health insurance is supposed to be there when we need it. We pay into it each month so that we can afford to get the health care we need when we are sick or injured. But what happens if your insurance company denies your claim? There are many valid reasons why a claim may be denied. Here are five of them:

1. You Waited Too Long to File the Claim

Every insurance company has its own "window of opportunity" to file a claim. Most insurers give policyholders 90 days from the date of service to file a claim, but some only allow 30 days to file. Medicare allows a year.

If you waited too long from the time of service to file a claim, it will be rejected.

2. The Insurance Claim Was Lost and Expired

Insurance companies sometimes lose, or misplace, claims. If a lost claim doesn't make it into the system before the deadline, it will be rejected – even if it's their fault.

The insurance company will likely tell you that there's nothing they can do, as the deadline has expired.

3. A Pre-Authorization Was Required

Many insurance companies require patients to obtain pre-authorization of services before receiving treatment. Pre-authorization is usually required for non-routine services, like surgery, hospitalization or behavioral care.

Your doctor should request pre-authorizations on your behalf, but sometimes, claims are denied afterwards. If your claim is denied but your doctor has already ordered tests, ask your doctor to talk to your insurance company on your behalf.

4. You Used a Provider that Wasn't in Your Network

If your insurer is an exclusive provider organization or a health maintenance organization, your claim may be denied if you used an out-of-network provider.

Using a provider outside of your network means that you've chosen a health care provider who hasn’t agreed to your insurer's terms of payment. If your claim is denied for this reason, you may be on the hook for the bill, or you may be required to pay a larger share of the bill.

5. The Bill Was Sent to the Wrong Insurer

The reason for your claim denial may be simple: the bill went to the wrong insurance company. If you've changed health insurance providers since the last time you visited your doctor, the office may have a different insurance provider on file.

Having two insurance companies on file can also cause confusion.

Check to make sure that your provider has the correct insurance company information.

What happens if your insurance company doesn't give you a reason for your claim denial? You can fight back, and the insurer may be liable for a bad faith claim.

According to Law Office of Matthew L. Sharp, "Insurance bad faith laws make it unlawful for an insurance company to fail to treat a customer in accordance with the duty of good faith and fair dealing. In general, insurance companies must fulfill the following obligations to their customers: Promptly and fully pay a claim covered by the insurance policy, conduct a fair and complete investigation before a claim is denied, and provide the customer with the factual and legal reason for denying any claim."

If your insurance company hasn't provided you with a valid reason for your claim denial, you may have legal recourse and should consider consulting with an attorney.