For what reasons can you be denied health insurance?

Pre-exisiting conditions and current lifestyle habits are both reasons for coverage denial. Additionally, the commission of insurance fraud may be a reason.

In general, all insurers have "underwriting guidelines" which define the parameters of the risks that they are willing to assume. If your health or related conditions do not fit within those parameters, you may be denied. Note, though, that the law of the state involved may prohibit the insurer from relying upon one or more reasons for denying an application for coverage.

Generally, the state insurance regulator must approve the underwriting guidelines that the insurer employs as a condition of getting authority to conduct business in the state.