835 Denial Combination
CO-170
Contractual Obligation · Claim-Level Adjustment
Coding ErrorWhat This Combination Means
This denial indicates that the service was billed by a provider type that is not authorized under the payer's contract to perform or bill for this specific service. The payer is enforcing contractual restrictions on which provider types can deliver certain services, and the billing provider does not meet the required criteria. The provider must write off the amount and cannot seek payment from the patient.
Financial Responsibility
provider writeoff
The provider is contractually required to write off the denied amount. The patient has no financial responsibility for this service because the denial is based on contractual provider type restrictions.
N/A
Appeal Success
Immediate (write-off)
Avg. Resolution
Easy
Difficulty
No
Appealable
Step-by-Step Resolution
Steps tailored specifically to this CO-170 combination — not generic advice.
- 1
Verify the billing provider type against contract terms
Confirm which provider types are authorized to bill for this specific service code under your payer contract to validate the denial.
- 2
Write off the denied amount
Post the contractual adjustment to the patient account as a provider write-off since CO denials cannot be billed to the patient.
- 3
Update billing protocols to prevent recurrence
Document provider type restrictions for this service and payer combination, and train staff to bill through an authorized provider type or refer patients accordingly for future encounters.
Specialty Context
How CO-170 typically presents across different practice types.
Dental
Common when general dentists bill for procedures restricted to oral surgeons or periodontists, such as certain implant placements or complex extractions that the plan requires a specialist to perform.
Medical
Frequent in scenarios where mid-level providers (NPs, PAs) bill for services that the contract restricts to physicians, or when non-specialty providers bill for services requiring board-certified specialists.
Behavioral Health
Often occurs when licensed counselors or social workers bill for services that the payer contract restricts to psychiatrists or psychologists, such as certain diagnostic evaluations or psychological testing.
Individual Code References
View the standalone definition for each code in this combination.
Medicare Contractor Guidance for CARC 170
FCSOThis denial is received when services furnished or ordered by a chiropractor are not related to treatment by means of manual manipulation of the spine to correct a subluxation and/or the claim submitted does not meet the requirements.
How to Prevent CARC 170 Denials
- ✓
Medicare coverage of chiropractic services is specifically limited to treatment by means of manual manipulation of the spine to correct a subluxation. All other diagnostic or therapeutic services furnished or ordered by a chiropractor are not covered by Medicare.
- ✓
Claims for chiropractic services should include: primary diagnosis = subluxation, secondary diagnosis = condition necessitating treatment, all diagnosis codes coded to highest level of specificity, date of initial visit or exacerbation.
- ✓
Include modifier AT to indicate active / corrective treatment to treat acute or chronic subluxation. Documentation in the patient's medical records must support that the service is reasonable and medically necessary.
- ✓
If you expect Medicare to deny the item or service (e.g. maintenance therapy) as not reasonable and necessary, you may include modifier GA (Signed ABN on file), GZ (Signed ABN not on file), or GY (Statutorily excluded).
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