Medical Coding Knowledge,
Rules & Decision Support
Search coding data, explore relationships, and apply version-aware CMS-derived rules with transparent source information. ICD-10-CM, HCPCS Level II, ICD-10-PCS and MS-DRG, built from official CMS, CDC, FDA and AHRQ releases.
Search a Code
Finding the code is the easy part.
MedCoder connects each code to its hierarchy, the tabular notes attached to it, the codes it excludes or must be sequenced with, and the CMS-derived rules that apply to a whole claim — procedure-to-procedure edits, published utilization limits, coverage policy and MS-DRG grouping. Every rule carries the source and release it came from. Facts are quoted from the published source files; the explanations around them are MedCoder’s, and labelled as such.
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Search a code
What does this code mean, and is it billable?
Official CMS title, billable status, inclusion terms, and the tabular notes attached to the code.
Look up E11.902
Follow its relationships
What does it exclude, what must be coded first, and what are the more specific options?
Chapter, block and category context, every billable child code, and the Excludes1, Code First and Use Additional Code notes that tie it to other codes.
Browse the registry03
Compare codes
Can these two codes be reported together?
Side-by-side Excludes1/Excludes2 relationships and sequencing notes between any two codes, quoted from the tabular list.
Compare E11.9 vs E10.904
Check a claim
Which CMS rules does this code list trip?
Excludes1 conflicts, sequencing instructions, Medicare Code Editor principal-diagnosis and age edits, 7th characters and POA — then, reported separately, the NCCI procedure-to-procedure edits and published MUE figures MedCoder holds, the modifiers on each line, and the Medicare NCD code lists CMS publishes. On an inpatient claim, CMS’s own grouper tables give the MS-DRG. Up to 25 codes, every pair.
Check a ClaimBeyond code lookup
MedCoder connects coding data with rules, relationships, coverage information and inpatient grouping logic, so a coder can understand not only what a code is, but how the related rules may bear on a coding decision. Every rule reported names the CMS source it came from and the release that source was published in.
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.
Claim Check
Check a code list against the applicable MedCoder coding rules and CMS-derived information.
Claim Check
Paste the codes from a claim. Run the CMS rules MedCoder supports against the whole list.
Up to 25 codes — a full institutional claim — checked pairwise and in sequence, deterministically, against the official FY2026 ICD-10-CM data and the CMS rules releases that cover your date of service:
Excludes1 / Excludes2
Every pair checked against the tabular notes, including notes inherited from the category level. Blocking conflicts are separated from allowed-with-documentation review items.
Sequencing
Code First and Use Additional Code instructions that one listed code aims at another, with the required order shown.
Principal diagnosis
Medicare Code Editor edits: unacceptable principal, manifestation-first, external-cause-first, and age conflicts when you supply an age.
Code validity
Non-billable headers flagged with their billable children listed; missing required 7th characters with the valid extensions; specificity conflicts within the same category; laterality pairs where a bilateral code exists.
Inpatient context
POA indicator requirements per CMS’s exempt list. Supply the inpatient details and MedCoder’s own implementation of CMS’s published MS-DRG grouper logic groups the claim, showing the DRG it grouped to and which codes moved it.
Date of service
Codes validated against the fiscal-year code set that was actually in effect on that date.
Procedure-to-procedure edits
Pairs of HCPCS Level II codes CMS lists as procedure-to-procedure edits, with the modifier indicator published for the pair. The rows MedCoder holds are a subset of the NCCI tables, never all of them.
Published utilization limits
The Medically Unlikely Edit value CMS publishes for a HCPCS Level II code, reported as a published threshold. A subset of the MUE tables, for the same licensing reason.
Modifier review
Each modifier submitted on a line, checked against the CMS HCPCS Level II modifier registry for the release that covers the date of service.
Coverage policy
A Medicare National Coverage Determination you choose, checked against the diagnosis code list CMS publishes for it. Local Coverage Determinations are licensed and never consulted — every result says so.
MS-DRG grouping
Supply the inpatient details and MedCoder’s own implementation of CMS’s published MS-DRG grouper logic groups the claim, showing the DRG it grouped to and which codes moved it.
Every finding quotes the official instruction it came from, so you can verify it — and cite it.
What it doesn’t do, on purpose: No payer-specific edits, no Outpatient Code Editor (OCE) logic, and no CPT — the Medically Unlikely Edits (MUE) and NCCI procedure-to-procedure edits it runs are HCPCS Level II only, because the CPT rows in those CMS files are AMA-licensed and not published here, so what it checks is a supported subset of each table and never the whole of it. Medicare National Coverage Determinations are checked only against the code lists CMS publishes; Local Coverage Determinations are licensed and not held. MS-DRG grouping is MedCoder’s own implementation of CMS’s published grouper logic, run against CMS’s published grouper tables; MedCoder is not certified, approved, endorsed, or operated by CMS. Where a release is not loaded the answer is “data unavailable”, which is not “no rule” and not “allowed”. It is a reference, not billing advice — a claim that passes here can still be denied on a policy this tool does not model.
No PHI. It needs codes and, optionally, a date of service and age — never names, record numbers, or notes. Codes are not logged or sent to third parties.
Every code set MedCoder covers
One search across all of them, or browse each registry on its own.
More reference tools
HCPCS modifiers
Pricing and payment modifiers for procedure codes.
ICD-10 codes by condition
Every ICD-10-CM code for a condition, grouped by AHRQ CCSR category.
Drugs & Chemicals index
Poisoning, adverse effect and underdosing T-codes by substance.
External Causes index
Mechanism-of-injury codes (V00-Y99) from the official alphabetic index.
Medical coding guides
Scenario guides to Excludes1 vs Excludes2, 7th characters, sequencing and more.
Code set updates
Every code added, deleted or revised in each ICD-10-CM release.
Coding questions
Coding decisions working coders ask about, answered from the official ICD-10-CM, ICD-10-PCS and HCPCS Level II sources.