Denial codes / CO-26
Denial code 26CO-26: Before coverage started
Expenses incurred before coverage started.
What to doCheck coverage, then resend
Often recoverableYes, when worked
The letters in front matter. CO means the office can't bill the patient for the amount; PR means the patient may owe it. The same number can appear with either, so read both parts.
Why dental offices see it
- Service date before the plan's effective date.
- The patient changed employers or plans and the new plan was not active yet.
What to do
- Verify the effective date with the insurer.
- If coverage was active, resend with proof of eligibility.
- If not, bill the previous plan or the patient.
Stop it next time
Run eligibility before each visit, especially at the start of a plan year.
How many CO-26 claims are in your report? The free check counts them, ranks them by dollars and deadline and drafts the letter. It runs in your browser; nothing is uploaded.
Plain-English paraphrase; the official code list is maintained by X12. Insurer rules vary; check the insurer's provider manual. Not legal advice.