CO B20 denial code
Claim adjustment reason code B20. Often reported as CO B20.
Service furnished by another provider
Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated .
What B20 means
The payer says another provider already furnished all or part of this service, so it reduced or denied your line.
B20 is used when the payer believes some or all of what you billed was provided, and likely billed, by someone else. Think of global surgical packages, bundled facility services or a split between providers.
The payer is not saying the service was not done. It is saying you are not the one to be paid for it, or not for all of it.
Group codes seen with B20
On a remittance, B20 comes after a group code. These are the ones it is most often reported with:
- CO B20 (Contractual Obligation): The provider's side of the ledger. The reduction comes from the payer contract or a rule the provider has to follow, and the patient normally cannot be billed for it.
The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.
Common causes
- Another provider billed the same service for the same date and was paid first.
- Post-operative care was included in the surgeon's global package.
- Care was provided under arrangement and should be billed by the facility or primary provider.
What to do next
- Find out which provider was paid for the service and for what portion.
- Check whether your claim needed a modifier showing your part of a shared or split service.
- Coordinate with the other provider if one of you billed in error.
- Appeal with documentation showing your separate involvement if the payer is wrong.
Related codes
- B10 (reason code) Reduced: component already paid
- B13 (reason code) Previously paid
- 97 (reason code) Service included in another payment
Source
Official wording: X12 Claim Adjustment Reason Codes list. The explanation on this page is our own plain-English wording, not the X12 text.
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