CO-210 denial code
Pre-certification not received in a timely fashion
How to fix it
Appeal where the delay was payer-caused or where clinical urgency prevented advance authorisation.
How to prevent it
Track authorisation request deadlines, not just requirements. Late authorisation denies like missing authorisation.
In practice
A patient is admitted urgently on a Friday evening. The plan requires notification within 24 hours; the practice calls on Monday morning, obtains authorisation, and the claim still returns CO-210.
The authorisation exists. What failed is that it was requested outside the window the plan set, and plans treat a late request the same way they treat a missing one.
The appeal has to address the delay rather than the necessity. Payer-side unavailability, clinical urgency preventing an advance request, and a request made through a channel the plan later disowned are the arguments that work.
What sits behind it
Urgent and emergency admissions are the main source, because the timing requirement collides with the clinical reality. Plans generally accommodate this where the record shows the admission was genuinely unplanned, but the accommodation has to be requested rather than assumed.
Weekends and holidays create a predictable trap. A notification window measured in hours can expire before the plan's line reopens, and documenting the attempt — the date, time and outcome of each call — is what supports the appeal afterwards.
The distinction from a missing authorisation is worth drawing when writing. An appeal arguing that authorisation was never required will fail where the plan clearly requires it; one arguing that the request was made as soon as reasonably possible engages the actual objection.
Related codes
Terms used here — Prior Authorization · Appeal · Denial
How we handle it — Prior Authorization · Denial Management · Revenue Cycle Management
Primary sources
The rules behind CO-210, at the bodies that publish them.
- CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F) (opens in a new tab)
Centers for Medicare & Medicaid Services — The rule imposing prior authorization decision timelines and API requirements on impacted payers. It is the single largest scheduled change to authorization workflow this decade.
- Medicare Coverage Database (LCD/NCD) (opens in a new tab)
Centers for Medicare & Medicaid Services — Searchable national and local coverage determinations. The direct answer to whether a diagnosis supports medical necessity for a given procedure.
- Medicare Claims Processing Manual (opens in a new tab)
Centers for Medicare & Medicaid Services — The operative manual for how Medicare claims must be coded, submitted, adjusted and appealed. When a payer policy and a vendor's advice disagree, this settles it.
Looking for a different code? Search all 190 CARC and RARC codes
Questions about CO-210
Ones addressing the delay rather than the necessity: the plan's line was unavailable, the admission was genuinely unplanned and clinically urgent, or the request was made through a channel the plan accepted and later disowned. Documented call attempts carry these appeals.
Generally yes where the record shows the admission was unplanned, but the accommodation has to be requested. A notification window measured in hours can expire before the plan's line reopens, so documenting each attempt with date and time is what supports the request.
The authorisation exists but arrived outside the required window, so an appeal arguing that authorisation was obtained misses the objection. The plan is not disputing that permission was granted; it is disputing when it was sought.
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