What Are The 10 Essential Steps Of Laboratory Billing Services?

Even if a lab performs thousands of tests every week, and gets them right, it can go out of pocket. The difficulty is seldom scientific. This typically begins by not having a diagnosis code, not having a CLIA certificate for the test or using it without the proper modifier. 

That is why laboratory billing services follow a structured workflow. Lab claims have their own fee schedule, certification rules, modifiers and some of the strictest medical necessity checks in healthcare.

This guide breaks the lab billing process into 10 essential steps, with the codes and checkpoints that matter at each stage. To see how CureCloudMD supports labs across the full revenue cycle, the homepage is a good place to start.

What Laboratory Billing Really Involves

Laboratory medical billing involves converting a diagnostic test that has been completed into a bill that is paid. It includes order intake, verification of insurance, coding, charge entry, claim submission, payment posting and follow-up of un-paid or denied claims. 

What makes it different from physician billing is the type of work being billed. Labs usually never see the patient. They depend on a referring provider for the order, the diagnosis and the patient’s insurance details. If any of that information is incomplete, the lab carries the financial risk.

Billing requirements also change by lab type:

• Pathology lab billing involves professional and technical components for surgical pathology, cytopathology and interpretation services.
• Clinical lab billing covers routine chemistry, hematology, urinalysis and microbiology panels billed in high volume.
• Toxicology laboratory billing depends on separating presumptive screens from definitive drug testing and meeting strict payer policies.
• Molecular lab billing handles genetic, pharmacogenomic and next-generation sequencing tests, which often require test registration and prior authorization.
• Census entry lab billing focuses on accurate data capture and demographic entry before claims are created.

The 10 Essential Steps of Laboratory Billing Services

A reliable lab billing process moves every test through the same checkpoints, from the first order to the final payment. Each of the following steps builds on the one before it, so a gap early in the workflow almost always shows up later as a denial. 

Step 1: Test Requisition Review and Order Validation

An extensive requisition is the beginning of each clean lab claim. It is much more cost effective to secure a gap at intake than to rectify it after it is denied. 

What a Complete Requisition Includes

• Patient Name, DOB, Gender, Address
• Provide the name of the ordering provider and their NPI.
• Specific tests ordered, not vague requests like “standard labs”
• ICD-10-CM diagnosis codes for each test
• Specimen collection date and time
• Insurance details, ideally with a copy of the card

Why the Collection Date Matters

The date of service or specimen collection for most lab tests will be the date of the test. The lack of a date or incorrect date raises issues of eligibility and timely filing later. 

A Simple Intake Rule

No diagnosis, no billing! Maintain the order until the missing information is provided by the ordering office. 

Step 2: Patient Registration and Insurance Eligibility Verification

One of the largest causes of lab claim denials continues to be errors in registration. Effective eligibility screening prevents them prior to testing. 

What to Verify

• Active coverage on the date of service
• Correct payer and plan type, such as Medicare, Medicaid, Medicare Advantage or commercial
• In-network status for the lab
• Lab-specific deductibles, copays and coinsurance
• Whether a lab benefit manager controls approvals

Take note of Network Restrictions 

Some plans send the lab work to preferred national labs. This check should be done prior to testing, and one might be denied or receive a much lower payment from an out-of-network independent lab. 

Step 3: Medical Necessity Review, ABNs and Prior Authorization

Only tests that are medically necessary for the diagnosis provided are paid for by the payer. The diagnosis must document the need for the test as supported by the appropriate NCD or LCD for Medicare. 

Frequency Limits

Tests such as lipid panels, HbA1c and thyroid testing carry frequency limits. Ordering them too often without a supporting diagnosis leads to denials.

ABN Modifiers

When a Medicare test is likely to be denied, the patient should sign an Advance Beneficiary Notice before collection. The ABN status decides the modifier:

• GA: Expected denial, signed ABN on file
• GZ: Expected denial, no ABN, so the patient cannot be billed
• GX: Voluntary ABN for a statutorily excluded service
• GY: Service is statutorily non-covered

Prior Authorization for High-Cost Tests

Many commercial plans require prior authorization for molecular, genetic and pharmacogenomic tests. Skipping it usually means a denial that no appeal can fix.

Step 4: CLIA Certification and Credentialing Checks

Every lab testing human specimens in the US needs a CLIA certificate that matches the complexity of its tests. Medicare edits lab claims at the certificate level.

Reporting the CLIA Number

The CLIA number goes in item 23 of the CMS-1500, or loop 2300 (REF segment, qualifier X4) on the 837P. A missing or expired number means an instant denial.

Modifier QW for Waived Tests

CLIA waived tests on the CMS list need modifier QW to be recognized. A few long-standing codes, such as 81002 and 82270, do not need it, so always check the current list.

Payer Enrollment

Labs must be enrolled with each payer they bill. New or expanding labs should start medical credentialing early, since enrollment delays hold up cash flow.

Step 5: Accurate CPT, HCPCS and ICD-10-CM Coding

Coding is the core of lab billing and coding. Pathology and laboratory services fall in the CPT range 80047 to 89398, plus Proprietary Laboratory Analyses (PLA) codes ending in “U.”

Commonly Billed Lab CPT Codes

• 80048: Basic metabolic panel
• 80053: Comprehensive metabolic panel
• 80061: About Lipid panel
• 83036: Hemoglobin A1C
• 84443: Thyroid stimulating hormone (TSH)
• 85025: Complete blood count with automated differential
• 81001: Urinalysis, automated, with microscopy
• 87086: Urine culture, quantitative colony count
• 88305: Surgical pathology, Level IV

Panel Coding Rules

If all the elements of a defined panel are executed, charge the panel code. Unbundling is charging the components separately and will cause NCCI edits. 

Toxicology Codes

Presumptive drug screens are performed under the CPT 80305-80307. Only one HCPCS code per date of service is allowed to be used for definitive drug testing, depending on the type of drug(s) tested (codes G0480, G0481, G0482, G0483). G0659 can be used in physician office labs, if applicable. 

Molecular Test Identifiers

In Medicare MolDX jurisdictions, many molecular tests also need a registered DEX Z-Code on the claim. Without it, the claim denies automatically.

Supporting ICD-10-CM Codes

The diagnosis must be specific and support the test. Examples include:

• E11.9: Type 2 diabetes without complications
• E78.5: Hyperlipidemia, unspecified
• Z79.899: Other long-term drug therapy
• Z01.812: Preprocedural laboratory examination

Helpful Coding Resources

Labs can access CureCloudMD’s laboratory codes and guidelines, CPT codes library and common ICD-10 codes. If your team is no longer capable of handling the volume, medical coding services are certified and maintain accuracy. 

Step 6: Applying Lab Modifiers Correctly

Modifiers provide explanations for code alone. There are a handful of modifiers that get the job done in lab billing and payers scrutinize them.

Modifier 90: Reference Laboratory

Used when the billing lab sends a specimen to an outside lab. For Medicare Part B, only independent clinical labs (specialty code 69) can bill referred tests, and the reference lab’s CLIA number must appear on the claim.

Modifier 91: Repeat Clinical Diagnostic Test

Used when the same test is repeated on the same day for the same patient to get new results. It does not apply to repeats caused by specimen or equipment problems.

Modifier 59 or XU: Distinct Service

When a test is done again on the same day in the same patient to obtain new results. It is not used for repeats associated with specimen or equipment issues. 

Avoid Modifier Overuse

Avoid these shortcuts with 59 and 91, since they are flagged as a red flag by auditors. Correct use of modifiers is detailed in CureCloudMD’s modifiers resource. 

Step 7: Charge Entry and Fee Schedule Alignment

Once coding is completed, charges enter into the billing system. Accurate charge entry services ensure that each line is verified prior to being a claim. 

LIS Integration

A direct interface between the Laboratory Information System and billing software reduces manual keying. In high-volume labs, even small typing errors multiply quickly.

CLFS and PAMA Updates

Most lab tests are paid by Medicare at the Clinical Laboratory Fee Schedule (CLFS) which is updated quarterly. The Consolidated Appropriations Act, 2026 requires labs to submit private payer data from May 1 – July 31, 2026, and new rates will be effective January 1, 2027. 

The same law delayed the phase-in of CLFS rate reductions to 2027 through 2029. Labs should follow the CMS CLFS and PAMA reporting page for final rates.

Specimen Collection and Travel Charges

• 36415: Routine venipuncture
• G0471: Collection from a SNF patient or by a lab for a home health agency
• P9603: Travel allowance, per mile
• P9604: Travel allowance, flat rate

Travel allowance is only payable when a specimen collection fee is also payable.

Step 8: Claim Scrubbing and Submission

All claims should be sent through a scrubber. Here are the places that most unnecessary denials are prevented from happening. 

What a Claim Scrubber Checks

• Valid NPIs, CLIA numbers and demographics
• Diagnosis codes that meet NCD and LCD rules
• NCCI edits and medically unlikely edit (MUE) limits
• Missing or incorrect modifiers
• Z-codes and/or test registration as determined by the specific needs of the payer 

Choosing the Right Claim Format

Independent labs usually bill on the CMS-1500 or 837P. Hospital outreach labs billing non-patient specimens often use the UB-04 or 837I with type of bill 14X.

Timely Filing Limits

Medicare provides 12 months after the date of service. Many commercial payers will pay a lot less, up to 90 days, so claiming daily is the best option. 

Step 9: Payment Posting and Reconciliation

Payers send back an Electronic Remittance Advice (ERA or 835 file) that reflects the payment or adjustment and/or denial. Matching each payment to the proper claim line through careful payment posting. 

What Posting Reveals

• Underpayments for contracted rates or CLFS
• Overall denial patterns by payers and test or referred provider.
• Patients’ balances ready for statements
• Adjustments that are not in accordance with the payer contracts 

Bank Reconciliation

Deposits should be matched to payments that are posted. This helps to prevent the loss of any money between ERA and bank account. 

Step 10: Denial Management, AR Follow-Up and Compliance Audits

Every lab sees some denials. High-performing labs simply respond faster and fix the root cause.

Working Denials

Effective claim denial management sorts denials by reason, corrects fixable claims and appeals wrongful ones with documentation.

Following Up on Aging AR

Lab AR grows quickly because of volume. Dedicated AR recovery services work aging buckets in order, starting with high-value and time-sensitive claims.

Regular Compliance Audits

Labs face scrutiny under the Anti-Kickback Statute, Stark Law, EKRA and HIPAA. Periodic audits of coding, ordering patterns, ABN use and modifier frequency catch risks before an auditor does.

Key Lab Billing Metrics Worth Tracking

Measuring performance makes the 10 steps a system to improve. These metrics should be reviewed in labs at least once a month: 

• Clean claim rate: The share of claims accepted without errors on first submission
• First-pass resolution rate: Claims paid on the first attempt without rework
• Denial rate: Broken down by payer, denial reason and test type
• Days in AR: The average time it takes to collect payment
• Net collection rate: Collections compared to what the lab was entitled to collect
• Missing information rate: Requisitions that arrived incomplete from referring providers

Tracking these numbers by referring provider is especially useful, because a small number of ordering offices often cause a large share of missing diagnosis and demographic problems.

In-House vs. Outsourced Laboratory Billing

Both models can work. The right choice depends on your lab’s size, test menu and growth plans.

In-House Billing

It gives direct control but needs trained staff, software, clearinghouse fees and ongoing education on code and payer changes.

Outsourced Billing

It shifts the workload to a team that handles lab rules daily. This helps growing labs, multi-state operations and labs adding toxicology or molecular testing.

State-Specific Support

Medicaid and commercial payer rules vary by state. CureCloudMD supports laboratory billing services in California, Florida, Texas and New York, among other states.

How CureCloudMD Supports Laboratory Revenue Cycle Management

CureCloudMD works with pathology, clinical, toxicology, molecular and census entry labs across all 10 steps. Its AAPC-certified billers and coders manage everything from requisition review to denial follow-up in one workflow.

The team works inside your existing LIS or billing software. Compliance reviews cover CMS rules, PAMA, EKRA and the Anti-Kickback Statute.

Labs looking for a wider view of financial performance can also explore CureCloudMD’s revenue cycle management services.