CO-288 denial code
No referral on file. Different animal from prior authorization: a referral is the PCP directing the patient to you, required by gatekeeper-model plans, and the payer can't find one for this claim.
CO — Contractual Obligation. The write-off is yours. You agreed to it in your contract with the payer, and you cannot bill the patient for it.
Why you got it
- 1The patient's HMO requires PCP referrals and nobody obtained one before the visit.
- 2A referral exists but expired, ran out of visits, or names a different provider or specialty.
- 3The referral was issued but never transmitted — it lives in the PCP's system and nowhere the payer can see.
How do I fix a CO-288 denial?
- If a referral existed, this is the easy appeal: obtain the referral record from the PCP and submit it with the claim numbers.
- If not, contact the PCP about a retroactive referral — plans vary on whether and how far back they allow it, and the PCP's cooperation decides it.
- Failing both, appeal on circumstances if they warrant (urgent need, plan's own directory error) — and note the CO grouping: without a cure, this is your write-off, not the patient's bill.
Writing the appeal?
Our free generator drafts a CO-288 appeal letter that opens with the argument above — it runs entirely in your browser, so the claim details never leave your screen. No signup.
Generate the appeal letterHow to stop the next one
Make 'does this plan require a referral, and do we have it' a scheduling question for every gatekeeper plan. The referral requirement is knowable from the eligibility response; the denial is only inevitable if nobody looks.
Our diagnosis scrubber will not catch this one. CO-288 is driven by procedure codes, modifiers, or eligibility rather than by the diagnosis set — and procedure-side checking needs CPT codes, which aren’t included yet. We would rather tell you that than sell you a tool that quietly misses your most common denial.
If denials like this are a volume problem rather than a one-off, the denial management page explains how the paid workspace catches the coding causes on every claim, and the free ICD-10-CM lookup shows the coding notes behind any diagnosis code on the remittance.