Health insurers look for reliable, published evidence such as evidence-based guidelines put forth by medical specialty societies to craft their coverage policies. These guidelines generate both beneficial and controversial consequences on policies. Coverage policies aim to address the most typical clinical presentations. The American Academy of Neurology guideline for IV immunoglobulin strengthens the case for coverage when it is used to treat Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy. The guideline is less likely to strengthen coverage for several other diagnoses with lower levels of evidence. The responsibility to clarify specific situations when patient need falls outside of what is considered to be routine evaluation or treatment rests heavily on the physician. Advice on appealing an unfavorable coverage decision is also provided to the reader.