CO-151 Denial Code: Information Does Not Support This Many/Frequency of Services
CO-151 is a claim adjustment reason code meaning payment was adjusted because the payer deems the submitted information does not support this many or this frequency of services. It fires on units above MUE limits, repeat tests inside frequency windows, and daily-limit edits. Fix the units or documentation, or appeal with clinical support.
- Group
- CO (Contractual Obligation)
- Category
- Units / frequency exceeds limits
- Appealable?
- Yes, with documentation supporting the units or repeat service
- Typical fix
- Correct units, split lines with proper modifiers, or appeal with records
What does denial code CO-151 mean?
CO-151 means "payment adjusted because the payer deems the information submitted does not support this many/frequency of services." The payer is not disputing that the service is covered; it is disputing the quantity: too many units on one line, too many occurrences in a window, or a repeat that arrived sooner than policy allows.
Example: a wound clinic bills CPT 97597 with 4 units for one encounter at $85.00 per unit, $340.00 total. The MUE for the code allows fewer units per day, so the ERA reads: billed $340.00, allowed $85.00 on 1 unit, CO-151 adjustment $255.00 on the excess units. Or a screening billed 10 months after the last one denies in full because the frequency window is 12 months.
Why did the claim get a CO-151?
- Units exceed the MUE for the code, sometimes from a genuine clinical situation, often from a keying error (minutes entered in the units field is the classic).
- Frequency limits: screenings, labs like A1c or lipid panels, imaging, and preventive services all carry per-period limits in Medicare NCDs, LCDs, and commercial policies.
- Repeat services without repeat modifiers, so a legitimate second test the same day looks like an unsupported extra unit; modifier 91 or 76 was missing.
- Bilateral or multi-site procedures stacked as units on one line instead of split with anatomic modifiers.
How do you fix and resubmit a CO-151 denial?
- Confirm what limit fired: check the code's MUE value on the CMS table and the payer's frequency policy. The remark codes (run them through the denial code lookup) usually distinguish units from frequency.
- If the units were a data-entry error, correct them and resubmit. Done in five minutes.
- If the units are real and the MUE adjudicates per line, split the service across lines with the appropriate modifiers (76, 91, anatomic modifiers, XS) and resubmit with documentation ready.
- If a frequency limit fired but the repeat was medically necessary, that is an appeal, not a resubmission: send the order, the clinical rationale, and the prior result that prompted the repeat.
How do you prevent CO-151 denials?
Load MUE values and payer frequency schedules into your scrubber so excessive units and early repeats are caught pre-submission. For recurring screenings and labs, check the last-performed date during scheduling, including services done elsewhere when the payer's portal shows history. Train charge entry on unit conversions for timed codes and J-code billing units, and document medical necessity for any planned above-limit quantity before the claim goes out, not after it comes back.
Can you appeal a CO-151 denial?
Yes, and CO-151 appeals are winnable when the record genuinely supports the volume: multi-site wounds, bilateral findings, medically necessary early repeats after abnormal results. Attach the operative or procedure note, quantify the units against the documentation line by line, and cite the payer's own policy or the MUE adjudication indicator that allows override. Calculate your deadline with the appeal deadline calculator and build the letter in the appeal letter generator, quoting the exact policy language on when excess units are payable.
Frequently asked questions
The payer decided the information on the claim does not justify how many units, or how often, you billed the service. It is a volume edit: units above the Medicare MUE value, a test repeated inside a frequency window, or a service billed more times per day or year than policy allows.
A Medically Unlikely Edit is the maximum units of a CPT code one provider would reasonably report for one patient on one day, published by CMS. Units beyond the MUE commonly return CO-151. Some MUEs are absolute; others are per-line and can be split across lines with appropriate modifiers when documented.
No. CO-119 means a benefit maximum was exhausted, a plan-design cap like 20 visits per year. CO-151 means the payer thinks the quantity or frequency itself is not supported for this patient, a clinical-edit judgment. CO-119 is about the benefit; CO-151 is about the claim.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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