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Denial code lookup

Claim adjustment reason codes tell you why a claim was denied — in language written for adjudication systems, not people. This translates the ones you actually see, with the fix and the prevention for each.

190 codes · Last updated September 1, 2026

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CO-97 CO-45 CO-16 CO-50 CO-29 PR-204 CO-15 CO-197 CO-4 CO-11 CO-18 CO-22 CO-27 CO-31 CO-59 CO-96 CO-109 CO-119 CO-151 CO-167 CO-B15 PR-1 PR-2 PR-3 CO-140 CO-204 PR-49 CO-55 CO-40 PR-B7 CO-185 CO-183 CO-198 CO-165 CO-62 CO-107 CO-236 CO-231 CO-234 CO-B10 CO-150 CO-17 CO-252 MA130 CO-26 CO-32 CO-253 CO-147 CO-222 CO-19 CO-24 CO-23 CO-170 CO-242 CO-6 CO-58 CO-181 N130 N657 CO-5 CO-7 CO-9 CO-10 CO-12 CO-13 CO-14 CO-20 CO-21 CO-28 CO-30 CO-33 CO-35 CO-38 CO-39 CO-42 CO-44 CO-47 CO-48 CO-51 CO-52 CO-53 CO-54 CO-56 CO-57 CO-60 CO-61 CO-63 CO-65 CO-95 CO-100 CO-101 CO-108 CO-110 CO-111 CO-112 CO-114 CO-115 CO-116 CO-117 CO-125 CO-129 CO-136 CO-138 CO-141 CO-142 CO-146 CO-148 CO-149 CO-152 CO-153 CO-154 CO-155 CO-163 CO-164 CO-166 CO-171 CO-172 CO-173 CO-174 CO-175 CO-176 CO-177 CO-178 CO-179 CO-180 CO-182 CO-184 CO-186 CO-188 CO-189 CO-190 CO-192 CO-193 CO-194 CO-196 CO-199 CO-200 CO-201 CO-202 CO-203 CO-206 CO-207 CO-208 CO-209 CO-210 CO-211 CO-213 CO-214 CO-216 CO-220 CO-223 CO-224 CO-226 CO-227 CO-228 CO-233 CO-237 CO-239 CO-240 CO-243 CO-246 CO-249 CO-250 CO-251 CO-256 CO-261 CO-272 CO-273 CO-275 CO-276 CO-284 CO-286 CO-287 CO-288 CO-296 CO-299 CO-302 CO-A1 CO-B12 CO-B13 CO-B14 CO-B16 CO-B18 CO-B20 CO-B22 CO-B23 CO-D18 CO-D21 CO-P12 CO-P13

How to use this

Reading a denial properly

A remittance carries two kinds of code. The CARC (Claim Adjustment Reason Code) states the reason for the adjustment. The RARC (Remittance Advice Remark Code) adds detail. The two are meant to be read together, and reading only the CARC is why so many denials get worked incorrectly.

CO-16 is the clearest example. On its own it means only that required information is missing — it tells you nothing about what. The accompanying RARC names the actual field. Practices that work CO-16 denials without reading the RARC end up guessing.

The prefix matters too. CO means contractual obligation, which generally cannot be billed to the patient. PR means patient responsibility, which can. Misreading a CO as a PR and billing the patient is both a collection failure and a contractual problem.

Finally, aggregate them. A single denial is a claim problem; the same reason code appearing forty times a month is a process problem with a specific owner, and that is the one worth fixing.

Stop working the same denial forty times

A free billing audit aggregates your denials by reason code and payer, and tells you which upstream process is generating them.

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