Health insurance denial & claim adjustment codes

What health insurance denial code 31 means on your EOB

The plan cannot match you to a member record. Almost always a data-entry problem, not a coverage decision.

What usually causes it

• The member ID was mistyped.
• Name or date of birth do not match.
• The wrong plan was billed.

The documents that decide it

• Your insurance card.
• The claim as submitted.
• Your member record with the plan.

What to do next

Give the provider a fresh copy of your card and ask them to refile. This should never reach you as a bill.

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.