Denial codes

Get every denial code cleared and the claim paid

Plain answers for the codes on your remits, written toward one outcome: the denial cleared and the claim paid.

Every code points at a fixable problem

Each adjustment on an electronic remittance pairs a group code with a claim adjustment reason code. The group code is one of CO, PR, OA or PI, and the reason code says why the payer adjusted it. Both code sets are maintained by X12. X12 reason codes

Each guide below starts from the code on your remit and works toward a paid claim. WeBill Health maintains internal payer rule libraries organized by specialty and by carrier, and every claim receives Human Expert Review against them before it goes out. For the pattern behind repeat denials, read the Denial Root Cause Playbook.

Choose a denial code

Sources

Denial Defense 2.0

Root cause denial work that closes the documentation gaps behind repeat denials before they disrupt your revenue cycle.

98%

clean claim rate

40%

A/R reduction within 90 days

500+

payer rulesets in our rule libraries

See Denial Defense 2.0

Questions practices ask

What do CO, PR and OA mean on a denial?

They are claim adjustment group codes. X12 names CO Contractual Obligation, PR Patient Responsibility and OA Other Adjustment. X12 group codes

How long do I have to fix a denied Medicare claim?

Medicare claims must reach the contractor within one calendar year, 12 months, of the date of service, or Medicare will deny them. Commercial payers set their own limits in your contract. Noridian, Timely Filing

What does WeBill Health do about repeat denials?

We trace each repeat denial to its root cause and fix it before the next claim goes out. A person updates the payer rule library when a policy changes, and a person applies it to your claims.

Reviewed by Tyler Nguyen, Denial Defense Manager, on November 4, 2026. Facts verified November 1, 2026.

Find the denials that keep coming back

The Revenue Defense Audit is a free, forensic review of your claims and A/R by the team that would work your account. It maps your denial patterns by payer and code, with the root cause behind each one.

Request a Revenue Defense Audit