CO-223 denial code
Adjustment for mandated federal, state or local law
How to fix it
Confirm the adjustment is correct. Generally not appealable.
How to prevent it
Understand which regulatory adjustments apply to your payer mix so they are expected rather than investigated.
The CO prefix marks this a contractual obligation. The balance is absorbed by the provider under the payer agreement and cannot be transferred to the patient.
In practice
A remittance carries a percentage reduction applied under a statutory requirement rather than the contract. The adjustment appears as CO-223 and no appeal route is offered.
Regulatory adjustments are applied by mandate and are generally not appealable, because the payer is complying with a requirement rather than exercising judgement.
Confirm the adjustment matches what the applicable rule requires and post it. The useful work is understanding which mandated adjustments apply to your payer mix so they are expected rather than investigated each time.
What sits behind it
The adjustments in this category vary and change with legislation. Sequestration reductions, state-mandated fee schedule adjustments and various statutory rate modifications have all appeared under this code, and each has its own basis and duration.
Because these are systematic rather than claim-specific, they are best modelled rather than worked. A practice that knows a fixed percentage reduction applies to a payer can build it into expected reimbursement, which turns a recurring surprise into a planning input.
The one thing worth checking is that the adjustment matches the mandate. A payer applying a larger reduction than the rule requires is not making a mandated adjustment, and that difference only becomes visible where the expected figure is known.
Related codes
Terms used here — Contractual Adjustment · Allowed Amount · Payment Posting
How we handle it — Revenue Cycle Management · Practice Analytics · AR Management
Primary sources
The rules behind CO-223, at the bodies that publish them.
- Medicare Physician Fee Schedule lookup (opens in a new tab)
Centers for Medicare & Medicaid Services — Official allowed amounts by CPT/HCPCS code and locality. The reference point most commercial contracts are written against as a percentage.
- 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.
- Claim Adjustment Reason Codes (CARC) (opens in a new tab)
X12 — The authoritative, maintained CARC list. Our denial code lookup explains these in plain English; X12 is where the canonical definitions live.
Looking for a different code? Search all 190 CARC and RARC codes
Questions about CO-223
Generally not, because the payer is applying a legal requirement rather than making a determination. What can be checked is whether the amount matches what the mandate actually requires, and a larger reduction than the rule specifies is worth raising.
Sequestration reductions, state-mandated fee schedule adjustments and various statutory rate modifications, each with its own basis and duration. The specific mix depends on payer type and jurisdiction, and it changes as legislation does.
No — they are systematic and predictable, so they belong in expected reimbursement modelling rather than in a denial queue. Knowing a fixed reduction applies to a payer turns a recurring surprise into a planning figure.
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