What does denial code CO-107 mean?

CO-107 means the payer could not find the related or qualifying service this claim depends on. Add-on codes, assistant surgeon lines, and post-operative care all require an anchor service, and without it the dependent line cannot be paid.

Why did CO-107 post when the primary service was billed?

Usually because of sequencing. If the dependent claim reached the payer before the primary finished adjudicating, the qualifying service did not exist in their system at the moment of processing. Confirm the primary has finalised, then resubmit the dependent claim unchanged.

CO-107: The related or qualifying service was not identified on the claim

CO-107 is a dependency denial. Certain services only exist in relation to another - add-on codes, assistant surgeon lines, post-operative care after a surgery billed elsewhere - and the payer cannot pay them without seeing the anchor. The single most common cause is a sequencing problem rather than a missing service: the dependent claim reached the payer before the primary one was adjudicated, so at the moment of processing the qualifying service genuinely did not exist in the payer's system.

What it means: This service is only payable alongside another one, and the payer cannot find the related or qualifying claim it depends on.
Who pays the balance: Contractual - the linkage is a claim-construction responsibility, not a patient one.
Group code CO: Contractual Obligation - the provider absorbs the balance and cannot bill the patient

Why CO-107 happens

An add-on code was billed without its primary procedure on the same claim.
The dependent claim was submitted before the primary claim finished adjudicating, so nothing matched at processing time.
The primary service was performed by a different provider or facility that has not billed it yet.
The two claims were submitted under different provider identifiers, so the payer could not connect them.
The primary claim was itself denied, leaving the dependent service with nothing to attach to.

How to fix a CO-107 denial

1
Identify which qualifying service the payer is looking for
The remark codes usually name the relationship. Add-on codes have a defined primary procedure; post-operative care attaches to a specific surgery with its own date and code.
2
Confirm the primary claim was received and adjudicated
Check the payer's claim status rather than your own submission log. A claim you sent is not a claim they processed, and the distinction is the whole cause here.
3
Resubmit once the primary has finalised
If the dependency simply arrived out of order, resubmitting after the primary adjudicates resolves it with no change to the claim itself.
4
Bill both lines on one claim where the payer expects that
Add-on codes generally have to appear on the same claim as their primary procedure. Splitting them across two claims produces this denial every time regardless of sequencing.

Preventing CO-107 denials

Keep add-on codes on the same claim as their primary procedure rather than letting the billing system split them.
Hold dependent claims until the primary is confirmed adjudicated when the two come from different providers.
Reconcile surgical and post-operative billing across entities so the anchor claim is known to have gone out first.

CO-107 frequently asked questions

What does denial code CO-107 mean?: CO-107 means the payer could not find the related or qualifying service this claim depends on. Add-on codes, assistant surgeon lines, and post-operative care all require an anchor service, and without it the dependent line cannot be paid.
Why did CO-107 post when the primary service was billed?: Usually because of sequencing. If the dependent claim reached the payer before the primary finished adjudicating, the qualifying service did not exist in their system at the moment of processing. Confirm the primary has finalised, then resubmit the dependent claim unchanged.

Related denial codes

CO-97 CO-18 CO-16 CO-234

Last reviewed August 5, 2026.

Denial code explanations are original plain-English summaries written for reference and are not the official X12 code descriptions. Payer handling of any code varies by contract - always verify against the remittance advice and your payer agreement before adjusting a claim.