CPT code 81401 – Tier 2, Level 2 molecular pathology procedure

Key takeaways

CPT Code 81401 is the Tier 2, Level 2 code for analyses named in its AMA list, such as ABL1 T315I or APOB common variants.

Genes with their own Tier 1 code never go under 81401. CYP2C19 is 81225, DPYD is 81232, JAK2 V617F is 81270 and PTEN is 81321-81323.

The same gene can sit under different levels. ACADM K304E alone is 81400, while the ACADM common-variant panel is 81401.

Medicare pays 81401 at $137.00 on the 2026 Clinical Laboratory Fee Schedule. MolDX contractors also require a DEX Z-Code on the claim.

Pabau, the practice management platform we build, checks every claim for missing details before it goes to the payer through Claim.MD.

CPT Code 81401: Official descriptor and Tier 2 classification

CPT Code 81401 is the American Medical Association (AMA) code for a Tier 2, Level 2 molecular pathology procedure. Labs report it only for the gene analyses printed in its parenthetical list, such as the ABL1 T315I variant or APOB common variants.

The official descriptor reads “Molecular pathology procedure, Level 2”. Its parenthetical gives four examples of the work it covers:

• 2-10 SNPs
• 1 methylated variant
• 1 somatic variant [typically using nonsequencing target variant analysis]
• detection of a dynamic mutation disorder/triplet repeat

The AMA’s CPT code set splits Tier 2 into nine levels, 81400 through 81408. Each level groups analyses of similar technical effort, from one germline variant at Level 1 to sequencing of more than 50 exons at Level 9.

Labs find the level by locating the exact gene and analysis in the AMA list. The table shows the descriptor examples and some listed analyses for Levels 1 to 4.

Rates are the national limitation amounts in the CMS Clinical Laboratory Fee Schedule 2026 file. Gene examples come from the AMA descriptors printed in the same file.

Which genes and procedures does CPT 81401 cover?

CPT 81401 covers only the dozens of analyses named in its AMA list. They fall into four groups: common-variant panels, single somatic variants, methylation tests, and fusion-gene translocation assays.

Each entry pairs a gene with one exact analysis. That is why one gene can need a different code when the lab runs a different test on it.

The analysis type decides the code, even within one gene. ACADM K304E tested alone is 81400, but the ACADM common-variant panel is 81401. PRSS1 common variants are 81401, while PRSS1 full gene sequencing moves to 81404.

Genes that have their own code

A gene with its own Tier 1 code is never billed under a Tier 2 level. Several genes still get misfiled under 81401, so check the Tier 1 range (81105-81383) before you open the Tier 2 list.

JAK2 V617F has its own guide, CPT Code 81270, covering indications and MolDX rules. When no Tier 1 or Tier 2 code names the analysis, the unlisted molecular pathology code CPT 81479 is the correct fallback.

CPT 81401 vs. 81402 vs. 81403: Choosing the correct tier

The correct Tier 2 level is the one whose AMA list names the exact gene and analysis. If the analysis appears under a code, use that code. If it appears under none, use 81479.

• Check Tier 1 first: if the gene and analysis have a gene-specific code in 81105-81383, use it and stop.
• Use 81400 when the analysis is a single listed germline variant, such as ACADM K304E or F5 HR2.
• Use 81401 when the gene and analysis appear in the Level 2 list, such as APOB R3500Q/R3500W or ABL1 T315I.
• Use 81402 for Level 3 entries, such as CYP21A2 or MEFV common variants and uniparental disomy STR analysis.
• Use 81403 for Level 4 entries, such as VHL deletion/duplication analysis or ANG full gene sequencing.
• Use 81479 when no Tier 1 or Tier 2 code lists the analysis. Attach a written test description and medical necessity documentation.

Medicare fee schedule rates for 81401 (2026)

Medicare pays CPT Code 81401 under the Clinical Laboratory Fee Schedule (CLFS), not the Physician Fee Schedule. CMS sets CLFS rates from private-payer data collected under the Protecting Access to Medicare Act (PAMA). The national rate for 81401 is $137.00 in both the 2025 and 2026 files.

The chart sets that rate against its Tier 2 neighbors and the Tier 1 codes most often misfiled as 81401.

Pull the current quarterly file from the CMS CLFS page before you set expectations, since CMS can revise rates each quarter. CLFS rates carry no geographic adjustment and no professional or technical component split.

Commercial payer rates depend on each lab contract and can sit above or below the CLFS rate. Most payers do not publish them, so labs confirm them through their contracts or fee schedule requests.

ICD-10 codes that support medical necessity for 81401

The ICD-10-CM code on an 81401 claim must reflect the clinical reason for the specific gene analysis. A general “genetic testing” or screening code rarely supports it. Pairing 81401 with a diagnosis your MAC does not accept is the most common denial trigger for this code.

Link the ICD-10 code to the 81401 line itself, not only the claim header. Before billing, check the diagnosis against your MAC’s current coverage article, since the covered code and gene combinations change with each update.

Medicare and commercial payer coverage policies

Medicare coverage for CPT Code 81401 is local, so the rules depend on your Medicare Administrative Contractor (MAC). Wellpoint Federal, formerly NGS, publishes billing and coding article A56199 under LCD L35000 (Molecular Pathology Procedures). It lists covered and non-covered Tier 2 code and gene combinations.

In MolDX jurisdictions (Palmetto GBA, Noridian, WPS and CGS), labs must register each test in the DEX registry first. The Z-Code from that registration goes on every 81401 claim line. Each contractor’s policy is listed in the CMS Medicare Coverage Database.

• Medicare: Paid under the CLFS when paired with a diagnosis the MAC accepts. Medicare itself requires no prior authorization. A signed Advance Beneficiary Notice (ABN) is needed before testing if you expect a medical necessity denial.
• UnitedHealthcare: UHC publishes a dedicated Tier 2 Molecular Pathology Procedures policy that may require prior authorization for 81401. Check the UHC provider portal for current requirements before the test is ordered.
• Other commercial payers: Coverage and prior authorization rules vary. Many follow Medicare criteria with their own clinical addenda, and they require prior authorization more often than Medicare does.
• Medicaid: Coverage varies by state. Some states cover Tier 2 molecular pathology for listed indications, while others review each request. Confirm with the state’s fee-for-service or managed Medicaid program before billing.

Documentation requirements for an 81401 claim

An 81401 claim passes audit only when the record contains each element below. Missing any one of them can trigger a documentation denial or a recoupment after a post-payment audit.

1. Ordering physician NPI and credentials – the ordering clinician’s full name, NPI and specialty must appear on both the lab requisition and the claim.
2. Clinical indication linked to a covered ICD-10 code – the reason for the test must map to a diagnosis your MAC covers. “Genetic testing requested” alone is not enough.
3. Specific gene and variant being analyzed – the requisition and the report must name the exact gene (eg, APOB) and analysis (eg, R3500Q/R3500W common variants). A generic panel description does not qualify.
4. Lab report matching the ordered test – the final report must reference the same gene and variant as the requisition. Any mismatch between order and report is a red flag in audit.
5. ABN when coverage is doubtful – if the indication falls outside the MAC policy, the patient signs the ABN before the test, not after the denial.

Structured order forms that capture gene, analysis type and ICD-10 code at order entry prevent most of these denials. Medical billing compliance frameworks put these checkpoints into the front-end ordering process rather than fixing them after a denial.

Common denial reasons for CPT Code 81401 and how to appeal

CPT Code 81401 claims face a predictable set of denials, and front-end edits prevent most of them. The table maps each common denial code to its root cause and the fix for resubmission or appeal.

For Medicare, file a redetermination within 120 days of the initial determination. If that fails, request reconsideration by the Qualified Independent Contractor (QIC) within 180 days of the redetermination decision.

Peer-reviewed evidence on the clinical utility of the specific analysis strengthens an appeal. For CO-50 denials, cite the ACMG or NCCN guideline that supports the ordered test. Denial management workflows built around CARC tracking help structure these appeals. For CARC and RARC context, see the full list of medical billing denial codes.

Bundling and unbundling rules for molecular pathology codes

National Correct Coding Initiative (NCCI) edits govern which molecular pathology codes can be billed together on one date of service. The most common error in this family is billing an analysis twice under two levels.

ACADM shows how it happens. The 81401 common-variant panel already includes K304E, so adding 81400 for K304E on the same specimen bills that variant twice. Report the one code that matches the full analysis performed.

The second pattern is stacking several 814xx lines for a test that has its own code. A gene with a Tier 1 code, or a panel with its own MAAA or PLA code, is billed under that code alone.

• Same-day billing of multiple 814xx codes: Allowed when each code is a distinct listed analysis with its own medical necessity documentation. Not allowed when the tests together make up a panel with its own code.
• Modifier 59: Append it to 81401 only when the analysis is clinically distinct from another molecular code billed that day, and the record shows it. It signals that an NCCI edit does not apply; it never overrides one that does.
• Modifier 91: Used when the same analyte must be retested on the same day, which is rare in molecular pathology. It seldom applies to 81401.
• MAAA and PLA codes: A proprietary multianalyte assay with an algorithmic result is billed under its own MAAA or PLA code. It is never split into individual 814xx lines.

How claims management software reduces 81401 claim errors

Molecular pathology billing has more moving parts than routine lab work. Line-level ICD-10 linkage, prior authorization, NCCI edits and remittance reconciliation all give errors a way into the claim. A billing workflow built for lab claims covers six checkpoints:

1. Place of service: An independent laboratory bills 81401 with POS 81 on the professional claim. A hospital outpatient lab bills on the institutional claim instead.
2. ICD-10 linkage at the line level: The diagnosis must point to the 81401 line, not only the claim header. Header-only linkage causes problems on multi-line lab claims.
3. Prior authorization tracking: On 837P claims, the authorization number goes in the Loop 2300 REF segment. Capturing it at order entry prevents CO-197 denials.
4. Pre-submission checks: Validation before sending catches missing details while they are still easy to fix. That includes membership numbers, diagnosis pointers and the DEX Z-Code.
5. ERA and EOB reconciliation: When 81401 posts with CO-50 or CO-97, the remittance should open an appeal or rebill task. Posting the payment alone leaves the denial unworked.
6. ABN tracking: For doubtful indications, confirm a signed ABN is on file before the test. An ABN signed afterwards does not shift financial liability. Revenue cycle management frameworks build this into front-end ordering.

Pabau’s claims management software runs validation checks every time you go to send a claim. If a required detail is missing, the Send button stays disabled until the claim is complete.

Claims then go to thousands of US payers through the Claim.MD clearinghouse, with real-time eligibility checks and claim status tracked in Pabau. Electronic remittance advice flows back into the same workflow, so denied 81401 lines reach follow-up quickly. Clean claim submission standards show how that clearinghouse layer catches CPT and ICD-10 mismatches before they reach the payer.

Simplify molecular pathology claim submissions

Pabau checks every claim for missing details before it goes out, submits it through Claim.MD, and tracks status and remittances in one place. See how it reduces 81401 denials.

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Conclusion

Most 81401 denials start before the claim is built, when someone picks the code from the gene name alone. Check the Tier 1 range first, then the Level 2 list for the exact analysis. That one habit prevents the CYP2C19, DPYD and JAK2 misfilings that older guides still repeat.

The rest is discipline at order entry: a diagnosis your MAC accepts, a DEX Z-Code in MolDX states, and an ABN signed before the test. Book a demo to see how Pabau catches missing claim details before your molecular pathology claims reach the payer.

Continue your research

Need a framework for tracking claim denials by reason code? Electronic remittance advice explains how ERA files map adjustment codes to denial reasons and how to build automated routing workflows from ERA data.

Looking to verify payer eligibility before submitting 81401 claims? Insurance eligibility verification covers how real-time eligibility checks reduce non-covered-service denials at the point of order.

Want to understand the clearinghouse layer between lab and payer? Medical claims clearinghouse breaks down how 837P transactions are validated, edited, and transmitted to payers, and where CPT edit checks occur in the workflow.

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