ABA Buyer Intent Guide

The most common ABA denial codes, and how to prevent them

Most ABA denials cluster around a handful of codes, and most of them are preventable with the right gates in front of the claim rather than appeals behind it. Here is the short list and what actually stops each one.

Quick answer

The most common ABA denials are CO-197 (authorization absent), CO-16 (missing information), CO-97 (bundled, often 97153 versus 97155), CO-50 (not medically necessary as filed), CO-151 (payer says the information does not support this many units), and CO-29 (past the timely-filing limit). Real-time authorization and documentation gating prevents most of them. Not billing or legal advice.

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The short list

CO-197 is an absent authorization or precertification, and it is the most common single ABA denial. CO-16 means a claim or service lacks information needed to adjudicate. CO-97 means the service is bundled into another payment, which in ABA often shows up around 97153 delivered while 97155 supervision is billed. CO-50 means the payer did not consider the service medically necessary as filed. CO-151 means the payer says the information does not support this many units. CO-29 means the claim was filed after the timely-filing limit.

Prevent, do not appeal

Appeals are slow and often unpaid. The structural answer is to gate the claim before it exists: track authorizations in real time so scheduling cannot outrun them, require a signed compliant note and EVV before a session can close, and enforce filing clocks so nothing ages into CO-29. In the Infinite Suite OS demo, the Claims Gate and the Auth Utilization War Room show this pattern as labeled demo capabilities on fictional data.

Frequently asked questions

What is the most common ABA denial code?

CO-197, an absent authorization or precertification, is the most common single ABA denial. It usually means the authorization expired, was exhausted, or did not cover the billed code.

What causes CO-97 in ABA?

CO-97 means the service is bundled into another payment. In ABA it often appears around the relationship between 97153 direct treatment and 97155 protocol modification or supervision, when payer bundling rules treat overlapping time as included. Check the payer’s specific bundling policy.

How do you prevent timely-filing denials (CO-29)?

Enforce each payer’s filing clock inside the workflow so claims cannot age past the limit, and clear documentation gates quickly so a signed note is never the reason a claim sits. Preventing CO-29 is entirely a process problem.

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Denial codes and payer rules vary by plan and state. Figures describe common industry patterns, not a specific clinic. This page is general information, payer-neutral, and is not billing or legal advice.