Health insurance denial & claim adjustment codes

What health insurance denial code 26 means on your EOB

Service predates your coverage start. Same check: confirm the effective date the plan has on file.

What usually causes it

• The service occurred before the effective date.
• The effective date was recorded wrongly.
• A waiting period applied.

The documents that decide it

• Your enrollment record.
• Your actual effective date.
• The date of service.

What to do next

Enrollment effective-date errors are common after job changes. Confirm the date with your employer or exchange, not just the plan.

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.