Laboratory Billing Services
The Prospect Healthcare Solutions team provides laboratory billing services for independent clinical labs, hospital outreach labs, physician office labs, toxicology labs, molecular diagnostics labs and pathology groups. We handle coding, claim submission, denials and A/R follow-up so your team can focus on testing.
Lab claims fail for reasons other specialties rarely see: a CLIA certificate that doesn’t cover the test, a missing QW modifier, no ABN for a test Medicare may not cover, a molecular claim without its DEX Z-Code, or a drug-testing panel billed at the wrong level. We check each of these before a claim goes out.
What Can Our Billing Service Do for Laboratories?
We run the full lab revenue cycle:
- Requisition review: ordering provider NPI, ICD-10 codes that support medical necessity, and tests that match the order.
- Eligibility and ABNs: insurance checks before testing, and Advance Beneficiary Notice tracking for Medicare tests that may not be covered.
- Coding and charge entry: CPT, HCPCS and PLA codes with correct units and modifiers (such as 59, 91 and QW).
- Claims: CMS-1500 / 837P or UB-04 / 837I, with the CLIA number where the payer requires it.
- Payment posting, denials and appeals, with A/R follow-up by payer.
- Patient statements and balance follow-up.
- Monthly reports on collections, denials and A/R by payer and test.
Lab Billing Rules We Check on Every Claim
- CLIA certificate and test complexity. A lab needs a CLIA certificate that covers the complexity of each test it runs (certificate of waiver, provider-performed microscopy, registration, compliance or accreditation). On paper Medicare claims the 10-digit CLIA number goes in item 23 of the CMS-1500, and waived tests that require it carry the QW modifier.
- Medical necessity. Medicare lab national and local coverage determinations (NCDs and LCDs) list the diagnoses that support each test. Screening tests are covered only when Medicare specifically covers them.
- ABNs. When Medicare may deny a test as not medically necessary, the patient signs an Advance Beneficiary Notice before the specimen is collected. Modifier GA reports a signed ABN; GZ reports an expected denial without one.
- Date of service and the 14-day rule. For specimens collected during a hospital stay or outpatient visit, the hospital usually bills and the 14-day rule sets the date of service. For molecular pathology tests and advanced diagnostic laboratory tests (ADLTs) that meet CMS's conditions, the performing lab bills Medicare directly.
- MolDX Z-Codes. In MolDX states, Medicare claims for molecular tests need the DEX Z-Code that identifies the test.
- Drug-testing limits. Payers limit how often presumptive and definitive drug tests are paid and how many drug classes are medically necessary.
A Common Lab Denial and How We Fix It
Example: a Medicare claim rejected for the CLIA number
The denial. A lab bills a CBC (85025) to Medicare and the claim comes back with CARC 16 (claim lacks information) and RARC MA120 (missing, incomplete or invalid CLIA certification number), or with CARC B7 when the lab’s certificate does not cover the test.
How we fix it:
- Find the cause. We check whether the CLIA number was missing from the claim, belonged to a different location, or was for a certificate type that doesn’t cover the test. A certificate of waiver, for example, covers only waived tests, and a CBC run on a non-waived analyzer is moderate complexity.
- Correct and resubmit. If the number was missing or wrong, we resubmit with the CLIA number of the lab that performed the test (item 23 on paper, loop 2300 REF X4 electronically).
- Escalate certificate gaps. If the certificate doesn’t cover the test, the claim can’t be fixed by billing alone. We tell the lab right away so it can update its certificate, and hold similar claims instead of sending more denials.
- Prevent the next one. We map each test code to the certificate that covers it, and set a claim check that stops any Medicare lab claim without a CLIA number.
Example: a molecular test denied without its Z-Code
The denial. A lab in a MolDX state bills a molecular test (for example, a tier 2 code from 81400–81408 or the unlisted code 81479) to Medicare without the DEX Z-Code, and the claim is rejected or denied for missing information.
How we fix it: we confirm the test is registered in the DEX registry and has a coverage decision, then resubmit with the Z-Code in the claim’s comment field (item 19 on paper, or the line note on electronic claims). If the test isn’t registered, we tell the lab, since the claim can’t be paid until it is. For new tests, we check registration before the lab’s first Medicare claim.
PAMA and the 2027 Clinical Laboratory Fee Schedule
Medicare pays most lab tests from the Clinical Laboratory Fee Schedule (CLFS). Under the Protecting Access to Medicare Act (PAMA), those rates are based on what private payers pay labs.
- The Consolidated Appropriations Act, 2026 (signed February 3, 2026) delayed CLFS cuts through December 31, 2026.
- Labs reported private payer data from January 1 to June 30, 2025, during a reporting window that ran from May 1 to July 31, 2026.
- CMS will use that data to set new rates starting January 1, 2027. Under current law, cuts of up to 15% per year can resume from 2027.
What labs should do now: list your top tests by Medicare volume, compare them with the new rates once CMS publishes them, and check payer contracts that are tied to Medicare rates. When new rates take effect, we compare every payment with them at posting so underpayments are caught.
Comprehensive Laboratory Billing Services for Labs of Every Size and Type
Independent Labs Billing
Independent labs bill Medicare under the Clinical Laboratory Fee Schedule on the CMS-1500 or 837P, with the CLIA number and the ordering provider's NPI on every claim. We manage requisitions from many referring offices, missing-information follow-up and A/R by payer.
Hospital Outreach Laboratory Billing
Hospital labs bill specimens from non-patients on the UB-04 or 837I (type of bill 14X) and tests for registered patients on the hospital claim. We apply the 14-day date-of-service rule and keep outreach charges separate from hospital encounters.
Physician Office Labs Billing
Physician office labs usually run CLIA-waived or moderate-complexity tests. We match each test to your CLIA certificate, add QW where required, bill venipuncture (36415) correctly and track tests that need an ABN.
Toxicology Laboratory Billing
Presumptive drug screens bill as 80305–80307. Definitive testing bills as G0480–G0483 for Medicare, based on the number of drug classes, and often as 80320–80377 for commercial payers. We check the order, drug classes and payer frequency limits before billing.
Molecular Diagnostics Labs Billing
Molecular tests use Tier 1 and Tier 2 codes (81105–81408), 81479 for unlisted tests and PLA codes (ending in U) for proprietary tests. We add DEX Z-Codes in MolDX states, track prior authorizations and follow up on high-value claims.
Pathology Laboratories Billing
Surgical pathology bills by specimen level (88300–88309), with professional (modifier 26) and technical (TC) components split when slides are read and processed in different places. We code from the final pathology report and match ICD-10 codes to the diagnosis.
Do Laboratory Billing Services Handle Coding?
Yes. Coding is part of every lab claim we bill. Our coders assign CPT, HCPCS and PLA codes from the requisition, link each test to the ICD-10 codes the ordering provider documented, and apply units and modifiers. If an order is missing a diagnosis or signature, we query it before billing. These are the code families labs use most:
| Codes | Used for |
|---|---|
| 80047–80081 | Organ and disease panels (for example, BMP, CMP, lipid panel) |
| 80305–80307 | Presumptive drug screening; see ICD-10 codes for drug screening |
| G0480–G0483 | Definitive drug testing for Medicare, by number of drug classes |
| 80320–80377 | Definitive drug testing by drug (many commercial payers) |
| 81105–81479 | Molecular pathology (Tier 1, Tier 2 and unlisted) |
| 0001U and up | Proprietary laboratory analyses (PLA codes) |
| 85025, 85027 | Complete blood count (CBC), with or without automated differential |
| 88300–88309 | Surgical pathology |
| 36415 | Routine venipuncture (blood draw); see the CPT code for a lab draw |
For more detail, see our guides to CBC CPT codes and the laboratory billing process. Need coding only? See our medical coding services.
How to Choose a Laboratory Billing Company
Lab billing is different from physician billing. Ask any laboratory billing company these questions before you sign:
- Lab experience: Which lab types do they bill today (clinical, toxicology, molecular, pathology), and for which payers?
- Coding depth: Can they code drug-testing levels, molecular tier and PLA codes, and pathology components?
- Compliance checks: How do they handle CLIA numbers, QW modifiers, ABNs, MolDX Z-Codes and the 14-day rule?
- Systems: Do they work with your laboratory information system (LIS) and clearinghouse, or ask you to switch?
- Denials and A/R: How quickly are denials worked, and is A/R reported by payer and by test?
- Reporting: Will you get monthly reports on collections, denials and A/R?
- Pricing: Is the fee a percentage of collections, per claim or flat, and what does it exclude?
- Security: Will they sign a HIPAA business associate agreement (BAA)?
We're happy to answer each of these for your lab. Contact us to set up a call.
Laboratory Billing FAQs
What do laboratory billing services include?
Requisition review, insurance eligibility checks, ABN tracking, coding (CPT, HCPCS and PLA codes), claim submission, payment posting, denial management, A/R follow-up and patient statements, for clinical, toxicology, molecular and pathology labs.
Where does the CLIA number go on a claim?
On a paper CMS-1500, the 10-digit CLIA number goes in item 23. On an electronic 837P claim, it goes in the CLIA reference field (loop 2300, REF X4). Use the CLIA number of the lab that performed the test.
When is the QW modifier required?
QW tells Medicare (and many other payers) that a test was performed under a CLIA certificate of waiver. Some waived test codes don't need it, so check CMS's list of waived tests for each code.
What is the difference between presumptive and definitive drug testing codes?
Presumptive tests (80305–80307) screen for drug classes. Definitive tests identify specific drugs: Medicare uses G0480–G0483, based on the number of drug classes tested, and many commercial payers use 80320–80377.
Do molecular tests need a Z-Code?
In MolDX states, Medicare claims for molecular diagnostic tests need the DEX Z-Code that identifies the test. Some commercial payers ask for it too.
What is the 14-day rule in lab billing?
It sets the date of service for tests on specimens collected during a hospital stay or outpatient visit, which decides whether the hospital or the lab bills. Molecular pathology tests and ADLTs that meet CMS's conditions can be billed by the performing lab directly.
Will Medicare lab payments drop in 2027?
They may. New Clinical Laboratory Fee Schedule rates based on private payer data take effect January 1, 2027, and under current law cuts of up to 15% per year can resume. Congress has delayed these cuts several times, so check for updates.
Related guides: Laboratory billing process and CMS guidelines · CBC CPT codes · Denial management · Credentialing and enrollment
Reach Out to Us for More Information
Have a question about billing for your lab? Tell us your lab type, test menu and main payers, and we'll explain how we'd handle your claims, from CLIA and ABN checks to denials and A/R. Whether you need full billing support or coding services only, contact Prospect Healthcare Solutions to talk it through.