Scope and limitations

MedCoder.ai is a medical coding reference and administrative decision-support tool built on federal source data. This page sets out what it supports, what it does not cover, what each kind of result means, and what still needs human or payer verification.

MedCoder reports what its supported source data and rules establish — and clearly tells you when they do not establish an answer.

MedCoder scope and coverage

Each area below is built from a named federal source and a stated release. Sources supply different kinds of information — a code set, an edit table, a code list or a policy record — and MedCoder reports only what each source provides.

ICD-10-CM: Diagnosis codes, titles, billable status and the tabular instructional notes, from the CMS and CDC release files, with the Medicare Code Editor edits.
HCPCS Level II: Codes, descriptors and published Medicare attributes, from the CMS release.
ICD-10-PCS: Inpatient procedure codes and tables, from the CMS release.
MS-DRG: MS-DRG reference pages, and grouping by MedCoder’s independent implementation of CMS-published grouper logic, with a decision trace.
Modifiers: HCPCS Level II modifiers from the CMS modifier registry, where a release covers the date of service.
NCCI PTP and MUE: The HCPCS Level II rows of the CMS procedure-to-procedure and Medically Unlikely Edit tables — a supported subset.
NCD: Checks against the structured diagnosis code lists CMS publishes for a National Coverage Determination.
LCD: Identification of potentially relevant Local Coverage Determinations, and reference pages for each, from the CMS Medicare Coverage Database.
Claim Check: Runs the supported checks above against a list of codes and reports each one separately, with its source and release.
Other federal sources: AHRQ clinical classifications, CMS-HCC mappings, the FDA National Drug Code Directory, CMS drug crosswalks and NLM MedlinePlus laboratory test descriptions — each identified on the Data Sources page.

Data Sources · Claim Check · LCD Policy Search · MS-DRG

What MedCoder does not cover

Some content is licensed and outside what MedCoder publishes. Other questions belong to the payer, the clinician, or the coder reviewing the record.

CPT codes, CPT descriptors, CPT modifiers and other AMA-licensed CPT content.
Complete NCCI and MUE tables — only the HCPCS Level II portion is held.
Payer-specific edits, policies and fee schedules, and Outpatient Code Editor (OCE) logic.
Coverage, payment and medical-necessity determinations.
Evaluation of whether a patient or service meets an LCD’s requirements.
Clinical diagnosis, interpretation of a patient’s test results, or treatment advice.
Licensed or proprietary coding commentary (see Licensed and copyrighted content, below).

CPT and NCCI/MUE limitations

CPT-keyed rows are excluded from ingestion. Therefore, MedCoder’s NCCI/PTP and MUE displays are a supported subset, not complete NCCI or MUE tables.

MedCoder does not include CPT codes, CPT descriptors, CPT modifiers or other AMA-licensed CPT content. The modifiers MedCoder lists are HCPCS Level II modifiers, which CMS publishes.

The CMS NCCI procedure-to-procedure (PTP) and Medically Unlikely Edit (MUE) tables are keyed on both HCPCS Level II and CPT codes, so the NCCI/PTP and MUE information in MedCoder represents only the supported HCPCS Level II portion of the source data.

The absence of an edit in MedCoder must not be interpreted as evidence that no CPT edit exists.

Where MedCoder does hold an edit, it is shown with CMS’s modifier indicator or MUE adjudication indicator, the care setting and the release it came from.

NCCI PTP rules · MUE rules · Guide: NCCI modifier indicators · Guide: MUE adjudication indicators

LCD and NCD limitations

LCD identification

MedCoder can identify potentially relevant LCDs and associated Billing & Coding Articles from supported CMS structured data — the ICD-10-CM code lists in the articles CMS links to each LCD — and shows each LCD’s MAC, jurisdiction, status, effective dates and CMS source.

LCD evaluation

Whether a patient’s or service’s circumstances satisfy an LCD is outside MedCoder’s scope. MedCoder presents the policy and its source; the policy text states the requirements.

MedCoder does not independently evaluate:

medical necessity
clinical documentation
frequency requirements
indications
contraindications
patient-specific circumstances
documentation requirements
payer-specific requirements

Finding an LCD means “review this policy,” not “this service is covered.”

Failure to identify an LCD does not mean that the service is covered. MedCoder relates LCDs to ICD-10-CM diagnosis codes through the article code lists, and an LCD can address a service without listing a diagnosis there.

NCD code-list checks

Supported NCD checks compare the submitted diagnosis codes with the structured code lists CMS publishes for a National Coverage Determination. Medical necessity is determined from the record and the policy, not by MedCoder.

A matching NCD code list does not by itself establish coverage. Absence of a matching code does not by itself establish non-coverage.

When the code list for a selected NCD is not loaded, the result is Data unavailable — not “allowed,” “covered” or “no rule.”

LCD Policy Search · NCD coverage rules · Guide: NCD diagnosis code lists

Claim Check limitations

No issue found does not mean approved, covered, or payable. It means no issue was identified by the supported MedCoder checks performed for the information provided.

Claim Check runs the supported MedCoder checks against the codes and claim attributes you enter, and reports each check separately with its source and release. It does not reduce them to a single pass/fail score.

Payers may also apply:

payer-specific edits
medical-necessity requirements
documentation requirements
policies not modeled by MedCoder
other claim-processing rules

Result statuses

These statuses are MedCoder findings, not payer approval or payment decisions.

No issue found: No issue was identified by the supported checks performed.
Review required: The available data identifies something that needs human review. It is not necessarily an error.
Blocking finding: A supported rule identified a blocking condition.
Informational: Additional context; not necessarily an error.
Data unavailable: Insufficient supported source data to make this determination. Not evidence that no rule exists.
Not applicable: The check does not apply to the submitted circumstances.
Missing input: The check could apply, but an input it needs was not provided.
Outside scope: A determination MedCoder does not make, such as payer policy or CPT-based rules.

Which inputs enable which checks

When a check needs an input that was not entered, the result says which one: “This check could not be evaluated because the date of service was not provided.”

Date of service: Date-sensitive rules: the code set in force on that date, the CMS rules releases that cover it, the LCD version in effect, and the MS-DRG fiscal year.
Patient age: Age-dependent checks: the Medicare Code Editor age edits.
Care setting: NCCI procedure-to-procedure edits and Medically Unlikely Edits, which CMS publishes separately for practitioner, hospital outpatient and DME supplier claims.
Selected NCD: The National Coverage Determination code-list check, which runs against the policy you choose.
Inpatient details: MS-DRG grouping: principal diagnosis, present-on-admission indicators, sex and discharge status.

Protected health information

Do not submit Protected Health Information (PHI).

Claim Check is designed to work from coding and claim attributes — codes, and where a check needs them, a date of service, age, sex or discharge status — rather than from information that identifies a patient. Do not enter names, dates of birth, addresses, medical record or member numbers, or free-text clinical notes.

Claim Check

Data availability and versioning

Data unavailable means MedCoder does not have sufficient supported source data to make that particular determination.

MedCoder is release-aware. Checks read the source release in effect on the date of service when one is given, and each result names the release it used. Code set changes are tracked release by release on the Code Set Updates pages.

It does not mean:

that no rule exists
that the code is allowed
that the service is covered
that the claim will be paid
that the payer has no edit
that no LCD or NCD applies

It is reported when a release is not loaded for the date in question, when the source does not publish the information in a structured form, or when the codes involved fall outside the content MedCoder holds. MedCoder reports the gap rather than filling it with an estimate.

Code Set Updates · Data Sources

MS-DRG implementation and verification

MedCoder independently implements the MS-DRG logic and tables CMS publishes for each fiscal year, and shows a trace of each grouping decision so a coder can review how the result was reached. It is not CMS software, and it is not certified, approved, endorsed, sponsored or operated by CMS.

The implementation is verified against CMS grouper software: its output is compared field by field with CMS’s own on a verification corpus covering the FY2023–FY2027 releases. The corpus was designed to exercise specific grouping pathways — each major diagnostic category, edge cases and refusals — and is not a statistical sample of real-world hospital claims.

That comparison is evidence of implementation fidelity on the tested cases. It does not establish universal real-world accuracy, and a grouping result does not guarantee reimbursement or payment.

How We Verify · MS-DRG grouping rules · Guide: MS-DRG grouper versions

Laboratory reference ranges

Laboratory reference ranges are shown only when a supported national or federal source publishes a usable reference value, and each range links to that source.

The absence of a reference range does not mean that the test has no reference range. Reference intervals may vary by laboratory, methodology, instrument, population, and other factors.

Laboratory pages describe tests and published reference values; they do not interpret a patient’s results.

Laboratory tests

Licensed and copyrighted content

This describes the product boundary. Where a code exists only in WHO ICD-10, MedCoder identifies it as not valid for US reporting and links to WHO’s own browser.

MedCoder publishes federal-source content. It does not reproduce:

the WHO ICD-10 base classification
AHA Coding Clinic advice
AMA CPT content
other proprietary or copyrighted coding commentary that MedCoder is not authorized to reproduce

Intended use

MedCoder is

A medical coding reference and administrative decision-support tool.

MedCoder is not

Complex claims should still be verified against applicable official source material and, when relevant, the specific payer’s policies and requirements.

an official CMS system
a payer claims processor
a clinical diagnostic system
a legal opinion
a formal coding audit
a guarantee of coverage or reimbursement

Source transparency

Every coding fact on MedCoder comes from a named federal source file. The Data Sources page records each file’s publisher, release, effective period, download link and checksum, and each result names the release it used.

No coding fact is AI-generated, and MedCoder does not supply a rule where a source is silent. Relationships MedCoder computes from those files, such as an MS-DRG grouping, are labeled as MedCoder-derived.

One vocabulary across the site

Supported result: MedCoder had sufficient supported source data to perform the check.
Review required: The available data identifies something that requires human review.
Data unavailable: MedCoder lacks sufficient supported source data to make that determination.
Not applicable: The rule or check does not apply to the submitted circumstances.

Data Sources · Code Set Updates · How We Verify

Frequently asked questions

Does MedCoder include CPT?

No. MedCoder does not include CPT codes, CPT descriptors, CPT modifiers or other AMA-licensed CPT content. It covers ICD-10-CM, ICD-10-PCS, HCPCS Level II and MS-DRG.

Does MedCoder check NCCI?

For HCPCS Level II codes, yes. CPT-keyed rows are excluded from ingestion, so MedCoder’s NCCI/PTP and MUE displays are a supported subset, not complete NCCI or MUE tables. The absence of an edit in MedCoder is not evidence that no CPT edit exists.

Does Claim Check determine coverage?

No. Claim Check reports supported coding-rule checks, NCD code-list checks and potentially relevant LCDs. Coverage determination remains with the payer.

Does MedCoder evaluate LCD requirements?

No. MedCoder identifies potentially relevant LCDs and their Billing & Coding Articles and presents the CMS source. Finding an LCD means “review this policy,” not “this service is covered.”

Does MedCoder determine medical necessity?

No. NCD checks compare codes with the code lists CMS publishes, and LCDs are identified for review. A matching code list does not by itself establish coverage, and a missing code does not by itself establish non-coverage.

Does MedCoder include payer edits?

No. Payer-specific edits, policies and fee schedules, and Outpatient Code Editor logic, are not modeled.

What does “data unavailable” mean?

Data unavailable means MedCoder does not have sufficient supported source data to make that particular determination. It does not mean that no rule exists, that the code is allowed, that the service is covered, that the claim will be paid, that the payer has no edit, or that no LCD or NCD applies.

Is MedCoder CMS certified?

No. MedCoder is an independent reference built on CMS and other federal source data. It is not certified, approved, endorsed, sponsored or operated by CMS.

Is the MS-DRG grouper CMS-approved?

No. It is MedCoder’s independent implementation of CMS-published MS-DRG logic, verified against CMS grouper software on a corpus designed to exercise specific pathways. That is evidence of implementation fidelity, not CMS approval or a guarantee of real-world accuracy.

Can I submit PHI?

No. Do not submit Protected Health Information (PHI). Claim Check is designed to work from coding and claim attributes — codes, and where a check needs them, a date of service, age, sex or discharge status — rather than from information that identifies a patient. Do not enter names, dates of birth, addresses, medical record or member numbers, or free-text clinical notes.

Does “no issue found” mean my claim will be paid?

No issue found does not mean approved, covered, or payable. It means no issue was identified by the supported MedCoder checks performed for the information provided.