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CO-33 Denial Code: Insured Has No Dependent Coverage

CO-33 means the insured subscriber has no dependent coverage, so a spouse, child, or other dependent billed under that policy isn't covered. The subscriber likely has single coverage; find the patient's own coverage or another plan.

Quick facts

Code
CO-33 (CARC 33)
Status
Active In use since January 1, 1995; last modified September 30, 2007.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The payer's common group. Don't bill the patient yet; find the patient's actual coverage.
  • PR (Patient Responsibility): Used when the payer assigns the amount to the patient because no dependent coverage exists under this policy. Confirm no other coverage applies before billing.
Official description
Insured has no dependent coverage.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-33 means

CARC 33 says the insured has no dependent coverage. The subscriber’s policy is set up for the subscriber only. When a claim arrives for a spouse, child, or other dependent under that policy, the payer denies it because no dependents are enrolled.

This is usually a registration problem rather than a coverage decision. Someone recorded the parent’s or spouse’s insurance as the patient’s, assuming family coverage. The patient may well have insurance, just not through this policy.

Common causes

  • Employee-only coverage mistaken for family coverage at registration.
  • Child billed under the wrong parent, when the other parent’s plan covers the child.
  • Coverage change from family to single during open enrollment or after a life event.
  • Dependent added recently but not yet effective on the date of service.
  • Subscriber information copied from another family member’s account.

How to fix it

  1. Run eligibility for the subscriber and look at the coverage level and listed dependents.
  2. Ask the patient or guardian which plan actually covers the patient.
  3. Bill the correct plan, updating boxes 1a, 4, 6, 7, and 11 to reflect the right subscriber and relationship.
  4. If dependents were recently added, confirm the effective date and ask the payer to reprocess once the update posts.
  5. If no coverage exists, bill the patient or guardian under your self-pay policy.

How to prevent it

  • Verify eligibility for the patient, not just the subscriber, before the visit.
  • Confirm which parent’s plan covers each child, especially in shared-custody situations.
  • Store insurance per patient in your system rather than copying it across family members.
  • Recheck coverage after open enrollment each year. See eligibility and COB denials.

Specialty notes

Pediatric practices and family medicine see CO-33 most often. In shared-custody situations, a court order may assign health coverage responsibility to one parent, which affects which plan should be billed first.

Remark codes that may appear with CO-33

  • N30 (Patient ineligible for this service.): The patient was ineligible for this service under this policy.
  • CO-32 (Our records indicate the patient is not an eligible dependent.): The plan has dependent coverage, but this person isn't an eligible dependent.
  • CO-34 (Insured has no coverage for newborns.): The plan doesn't cover newborns specifically.
  • CO-31 (Patient cannot be identified as our insured.): The payer can't identify the patient at all.
  • OA-22 (This care may be covered by another payer per coordination of benefits.): Another payer may be primary for the patient.

CO-33 FAQ

What's the difference between CO-33 and CO-32?

CO-33 says the subscriber's policy covers no dependents at all, such as employee-only coverage. CO-32 says the policy has dependent coverage, but this particular person doesn't qualify.

What should I do after a CO-33?

Ask the patient or guardian about any other coverage, such as the other parent's plan, the patient's own employer plan, Medicaid, or CHIP. Bill that coverage. If the subscriber recently added dependents, confirm the effective date and request reprocessing.

Could the payer be wrong?

Yes, for example if the subscriber changed from single to family coverage and the update hadn't posted. Have the subscriber confirm with their employer or plan.

Can I bill the subscriber for a dependent's CO-33 claim?

Only after you've confirmed no other coverage applies. The financially responsible party is usually the patient or, for a minor, the parent or guardian, depending on your financial policy and any custody arrangements.

Does CO-33 affect future visits?

Yes. Until the correct insurance is on the patient's account, every new claim will deny the same way. Update the registration before the next appointment.