Pathology Billing Services
Pathology billing services for anatomic pathology groups, hospital-based pathologists, independent labs and molecular testing labs. BilNow codes every specimen, splits the professional and technical components correctly and works each denial, so your pathologists stay with the slides.
98% First-Pass Claim Rate
Pathology Billing
Of Collections, No Setup Fee
No setup fee · No long-term contract · HIPAA-trained staff
Pathology Billing Services for Anatomic Pathology Groups and Labs
Pathology billing runs on specimens, not visits. One biopsy can create a surgical pathology charge, special stains, immunostains and a molecular test, each with its own unit rule and a professional and technical split. BilNow is a pathology billing company that handles anatomic pathology billing for groups, hospital-based pathologists and labs, and we check the unit count against the pathology report before a claim leaves.
Anatomic pathology groups
Surgical pathology, cytology and dermatopathology, billed per specimen, stain and antibody.
Hospital-based pathologists
Professional-component billing with modifier 26 under hospital agreements.
Independent and reference labs
Global and technical billing, client billing and third-party billing.
Molecular and genetic labs
Tier codes, PLA codes, Z-codes and date of service rules.
Clinical pathology
Chemistry, hematology and microbiology tests paid on the clinical lab fee schedule.
Labs that mostly run clinical tests can also read our laboratory billing services page.
Surgical Pathology Codes 88300–88309: Levels and Units Per Specimen
Surgical pathology has six levels. The level follows the type of specimen listed in the CPT descriptors, not the diagnosis or the pathologist’s time, so a colon polyp is Level IV whether it is benign or malignant.
| Code | Level | What it reports |
|---|---|---|
| 88300 | Level I | Gross examination only |
| 88302 | Level II | Gross and microscopic examination of simple specimens |
| 88304 | Level III | Gross and microscopic examination |
| 88305 | Level IV | Gross and microscopic examination; the most common level, such as colon polyps and prostate needle biopsies |
| 88307 | Level V | Gross and microscopic examination of complex specimens, including many tumor resections |
| 88309 | Level VI | Gross and microscopic examination of the most complex resections |
Each code is reported per specimen. Under Medicare’s NCCI rules, a specimen is tissue submitted for separate examination and diagnosis, and examining it separately must be reasonable and necessary. Polyps from different anatomic locations can each be a specimen, while several biopsies of one lesion count as one. We compare container labels, requisition and report before setting units.
Special Stains and Immunohistochemistry: 88312, 88313 and 88341–88344
Special stains are reported per stain per tissue source. 88312 is Group I, stains for microorganisms, and 88313 is Group II, all other stains, such as iron or reticulin. Several levels cut from one block and stained the same way count once, and controls are not billed.
| Code | What it reports | Unit rule |
|---|---|---|
| 88342 | First single antibody stain, per specimen | One unit for the first antibody |
| 88341 | Each additional single antibody stain (add-on to 88342) | One unit per further antibody on the same specimen |
| 88344 | Multiplex antibody stain | One unit per multiplex procedure with separate, necessary results |
Code 88343 was deleted in 2015 and is not reportable. Under NCCI, one immunostain run on several blocks of a specimen is one unit, and an antibody cocktail with one result is one unit. Medically unlikely edits (MUEs) cap units per code per day, and multi-specimen cases can reach them. Some payers set their own caps, and modifier 59 or XU is accepted only when the report documents each unit.
Professional vs Technical Component: Modifiers 26 and TC, and the 14-Day Rule
Most anatomic pathology codes can be split. The professional component, modifier 26, is the pathologist’s interpretation and report. The technical component, modifier TC, is slide preparation, stains and equipment. A lab that performs both reports the code with no modifier, as a global claim. Who may bill which part depends on where the specimen was collected, who owns the lab and the payer contract, so we map the arrangement first.
For Medicare, a lab test’s date of service is normally the date the specimen was collected, and a specimen stored more than 30 days is dated when it is taken out of storage. The 14-day rule covers a specimen collected during a hospital surgical procedure and tested later. The test date becomes the date of service, and the lab bills Medicare itself, only if the physician orders the test at least 14 days after discharge and the other conditions are met: collection was medically appropriate then, the result did not guide hospital care, and the test is reasonable and necessary. An earlier order is billed by the hospital, and the lab collects from the hospital.
Molecular and Genetic Testing: Tier Codes, PLA Codes and Z-Codes
Molecular pathology is coded in the 81xxx range by gene or procedure, with separate families for genomic sequencing panels and multianalyte assays. Proprietary Laboratory Analyses (PLA) codes are four digits plus the letter U and name one commercially available test from one laboratory or manufacturer. The AMA releases new ones quarterly.
A Z-Code is a five-character identifier for one molecular test, assigned through Palmetto’s DEX Diagnostics Exchange for the MolDX program. It goes on the claim with the CPT code so the payer knows exactly which test was billed.
NCCI blocks stacking: Tier 1 and Tier 2 codes are generally not added to a panel or PLA code that already tests the same analyte, and one analyte is not paid twice by two methods. Unlisted code 81479 is for tests no code describes. Molecular tests also have their own Medicare date of service exception after a hospital outpatient visit. Some commercial plans require prior approval for genetic tests, which our prior authorization services team requests.
Clinical Lab vs Anatomic Pathology, Client Billing and ABNs
Clinical pathology covers tests such as chemistry, hematology and microbiology. Anatomic pathology is tissue and cell diagnosis with a pathologist’s interpretation. Medicare pays clinical lab tests on the clinical laboratory fee schedule, usually with nothing owed by the patient, while pathologist services are paid on the physician fee schedule, where the patient share applies. Pathologist services follow the physician fee schedule, so it is worth reading what the 2027 proposed rule changes.
Client billing means the lab invoices the ordering hospital or practice at an agreed rate. Third-party billing means it bills the patient’s plan and the patient. A specimen is billed one way, never both. Covered Medicare services are billed to Medicare, and some states bar pass-through billing, cap markups or require the ordering practice to disclose the lab’s charge.
When Medicare may deny a Part B test as not reasonable and necessary, an Advance Beneficiary Notice (ABN) must be signed before the test to move liability to the patient. Any provider involved in the care can issue it, and CMS holds the billing provider responsible. Claims carry GA when an ABN is on file and GZ when none was issued but denial is expected.
Out-of-Network Surprise Billing: The No Surprises Act and Pathologists
Patients rarely choose their pathologist, so pathology is one of the ancillary specialties the No Surprises Act protects most firmly. At an in-network hospital, outpatient department, critical access hospital or ambulatory surgical center, an out-of-network pathologist cannot bill the patient above the in-network cost share, and the notice-and-consent waiver that works for some services is not allowed for pathology or laboratory services. A facility visit includes lab services even when the lab is off site.
The plan pays the pathologist, and independent dispute resolution settles a payment gap. Work ordered from a private office, outside a facility visit, generally falls outside this protection and follows the plan contract and state law. Contracting with the plans your hospitals use is the simpler path, and our medical credentialing services team handles enrollment.
Common Pathology Denials and How We Prevent Them
Most pathology denials come from a short list of causes.
Units over the limit
Specimen, stain or antibody units exceed an MUE or payer cap. We match units to the report first.
Bundling edits
A code pair bundles under an NCCI edit. We use modifier 59 or XU only when the report supports it.
Wrong 26 or TC
Global billed when the lab owns one component, or the modifier is missing. We set the split by contract.
Date of service errors
Collection date versus test date on stored or hospital-linked specimens. We apply the Medicare rule.
Medical necessity and ABN
Test not covered for the diagnosis, or GA and GZ missing. We check coverage policies before billing.
Molecular coding
Missing Z-code, stacked tier codes or an unlisted 81479 without records. We verify each code pair.
When a denial does arrive, our denial management services team works the appeal, and we track each payer’s timely filing limits so no claim ages out. BilNow charges a flat 2.7% of monthly collections with no setup fee and no long-term contract. Claims run at a 98% first-pass rate with denials under 5%.
Pathology Billing FAQs
What do pathology billing services include?
Pathology billing services cover charge capture by specimen, level and stain, modifier 26 and TC splits, claim scrubbing, submission, payment posting, denial follow-up and reporting. BilNow also handles client and third-party billing, Medicare ABN follow-up, molecular test coding and out-of-network disputes. We check each claim against the pathology report before it goes to the payer, while your pathologists keep their time for diagnosis.
How are surgical pathology specimens counted for 88300–88309?
Each code is reported per specimen, and the level follows the specimen type in the CPT descriptors, not the diagnosis. Under NCCI, a specimen is tissue submitted for separate examination, and separate examination must be reasonable and necessary. Polyps from different locations can be separate specimens, while several biopsies of one lesion are one. We compare container labels, requisition and report before setting the units.
How are special stains and immunohistochemistry coded?
Special stains use 88312 for microorganisms and 88313 for all other stains, one unit per stain per tissue source. Immunohistochemistry uses 88342 for the first antibody per specimen, 88341 for each additional single antibody and 88344 for multiplex stains. Code 88343 was deleted in 2015. MUEs and payer caps limit daily units, so the report must support each unit, and modifier 59 or XU is used only with documentation.
What do modifiers 26 and TC mean in pathology billing?
Modifier 26 is the professional component, the pathologist’s interpretation and report. Modifier TC is the technical component: slide preparation, stains and equipment. A provider that performs both reports the code with no modifier, as a global service. Which part you may bill depends on where the specimen was collected, who owns the lab and your payer contracts, so we confirm the arrangement before billing.
What is the Medicare 14-day rule for specimens?
Medicare normally dates a lab test by the day the specimen was collected. For a specimen collected during a hospital surgical procedure, the test date becomes the date of service, and the lab bills Medicare directly, only if the physician orders the test at least 14 days after discharge and other conditions are met. If the order comes sooner, the hospital bills Medicare and the lab collects from the hospital.
How are molecular and genetic tests billed?
Molecular tests are billed with 81xxx codes by gene or procedure, genomic sequencing and multianalyte codes, or a PLA code that names one specific test. Under the MolDX program, a Z-Code from the DEX Diagnostics Exchange identifies the test and is reported with the CPT code. NCCI does not allow stacking single-gene codes onto a panel testing the same analyte, and some plans require prior approval.
Does the No Surprises Act protect patients from out-of-network pathology bills?
Yes, for non-emergency care at in-network hospitals, outpatient departments, critical access hospitals and ambulatory surgical centers. An out-of-network pathologist cannot bill the patient above the in-network cost share, and the notice-and-consent waiver is not allowed for pathology or laboratory services. Lab work counts as part of the facility visit even when done off site. Payment gaps go to the plan and independent dispute resolution.
What does pathology billing cost with BilNow?
BilNow charges a flat 2.7% of monthly collections. There is no setup fee and no long-term contract, so the fee follows the money your practice or lab collects. Our claims run at a 98% first-pass rate with denials under 5%, and our HIPAA-trained staff work inside your existing system across more than 100 EHRs. Contact us for a review of your specimen volume and payer mix.
Prepared by the BilNow Editorial Team · Last updated October 2, 2026
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