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CMS coding rules

Four different questions get asked about one claim, and they are not the same question. MedCoder keeps them apart: what CMS published, which release it published it in, and what that does and does not tell a coder.

A code being valid is one fact. Whether two codes may be reported together is a second, how many units CMS expects on one date of service is a third, whether a Medicare policy speaks to the service is a fourth, and which inpatient group a whole claim classifies into is a fifth. Each is answered from a different CMS publication, on its own release schedule, and each can be answered while the others cannot.

So these are reported separately, never merged into a single verdict, and each carries its own source and version. None of them is an adjudication: MedCoder reports what CMS published and does not predict what a payer will do with a claim.

Four rule sets, four different questions

  • NCCI PTP — May these two codes be reported together? A coding relationship between a pair of codes. CMS publishes one code as Column 1 and the other as Column 2, with an indicator saying whether a modifier may ever permit separate reporting.
  • MUE — How many units does CMS publish for this code? A utilization threshold on a single code, not a relationship between two. Exceeding a published value is a finding about units, and nothing about it speaks to coverage or to correct pairing.
  • LCD / NCD — Does a Medicare coverage policy speak to this? Coverage policy, which is a different subject from coding correctness entirely. A correctly coded service may fall outside a coverage policy, and a service a policy supports may still be coded wrongly.
  • MS-DRG — Which inpatient group does the whole claim classify into? A classification of a complete inpatient stay, computed from the diagnoses, procedures and discharge information together — not a property of any one code on it.

The four rule sets

  • NCCI PTP — Supported CMS-derived procedure-to-procedure rules within MedCoder’s non-CPT scope.
  • MUE — Supported published Medicare utilization-edit information within MedCoder’s non-CPT scope.
  • LCD / NCD — Explore Medicare coverage-policy relationships, policy identifiers and effective dates, and where the policy boundary falls.
  • MS-DRG — Group inpatient cases using the applicable CMS-based MS-DRG version, with an explainable result.

What is true of all four

Every result names the CMS source it came from and the release version behind it, with the effective window that release covers and, where CMS publishes one, the rule’s own effective and deletion dates. A claim is evaluated against one release per source, never a mixture, and a release that does not cover the date of service is reported as not consulted rather than quietly skipped.

Data unavailable is its own answer. It means MedCoder could not look, not that there is nothing to find — it is never the same as no rule, no coverage, or allowed.

None of the four is a payer edit. MedCoder holds no payer-specific policy, no Outpatient Code Editor logic and no fee schedule, and a claim that raises nothing here can still be denied on a policy MedCoder does not model.

MedCoder is not certified by, endorsed by, approved by or affiliated with CMS. The data is published by CMS as works of the US federal government; the implementation reading it is MedCoder’s.

Run these rules on a code list

Claim Check applies all four to a list of codes at once and reports each one separately, with the release behind every finding. Claim Check.