Health insurance denial & claim adjustment codes

What health insurance denial code 204 means on your EOB

A plan-design denial rather than a clinical one. The question is whether your plan document actually excludes it, and exclusions are narrower than denial letters imply.

What usually causes it

• The service sits outside the plan's covered benefit categories.
• The drug or device is off-formulary.
• A benefit exception was never requested.

The documents that decide it

• Your full plan document, not the summary.
• The exclusion the plan is relying on, in its own words.
• Your provider's medical rationale.

What to do next

Ask the plan to cite the exact exclusion language. Then check it against your plan document — the language is often narrower than the denial suggests, and formulary exceptions exist.

This page explains what a code means. It is information, not advice — it does not tell you whether your specific claim should have been paid, and it is not legal, medical, or insurance advice. Your plan documents and your denial notice govern your situation.