Ancillary services can account for more than 10% of revenue in many specialty and primary care practices. But they can also create billing problems when claims are coded incorrectly, authorization is missed, or payer rules aren’t followed. If your practice offers lab work, imaging, physical therapy, or durable medical equipment alongside primary care, you’re already running ancillary services. That makes accurate billing essential if your practice wants to collect the revenue these services generate.
In this guide, we’ll explain the main types of ancillary services, give examples by practice setting, and walk through the billing and coding issues that can lead to denials.
What Are Ancillary Services in Healthcare?
Ancillary services are supportive or diagnostic services that work alongside the care a primary physician provides. They aren’t the primary treatment itself; they’re what makes an accurate diagnosis and complete treatment plan possible. A primary care physician, for example, might refer a patient for bloodwork, an X-ray, or physical therapy, each of those is an ancillary service.
In simple terms: if a service supports, confirms, or extends the care ordered by a primary provider, it’s ancillary.
These services can be delivered in-house (within the same practice) or through referral to an outside facility, such as a freestanding imaging center or independent lab.
The 3 Categories of Ancillary Services in Healthcare
Most ancillary services can be grouped into three main categories. The distinction matters because coding, coverage, and reimbursement requirements can vary by service type.
1. Diagnostic Ancillary Services
These help a provider detect or confirm a condition before treatment begins.
- Laboratory testing (bloodwork, urinalysis, biopsies)
- Diagnostic imaging (X-ray, CT, MRI, ultrasound)
- Cardiac and pulmonary testing (EKG, spirometry)
- Genetic testing
2. Therapeutic Ancillary Services
These services are used to treat a condition, manage symptoms, or support recovery.
- Physical, occupational, and speech therapy
- Mental health counseling
- Dialysis and infusion therapy
- Nutritional counseling
3. Custodial Ancillary Services
These services provide ongoing care or assistance for patients who need support beyond a standard office visit.
- Skilled nursing and nursing home care
- Home health care
- Hospice care
- Durable medical equipment (DME)
Examples of Ancillary Services in Healthcare by Setting
The services billed as ancillary care vary by practice and facility type. For example:
| Setting | Common Ancillary Services |
| Solo & group practices | In-house lab draws, basic imaging, DME dispensing |
| Hospitals | Radiology, pathology, respiratory therapy, cardiac diagnostics |
| Hospice | Pain management support, medical equipment, chaplaincy/counseling |
| Skilled nursing facilities (SNF) | Wound care, physical/occupational therapy, lab services |
If your practice provides any of these services, they may already represent a significant portion of your claims. That also means there are more coding, authorization, and reimbursement rules to manage.
Why Ancillary Services Matter for Practice Revenue
Ancillary services can be an important source of revenue for a medical practice, particularly when services are performed in-house. Industry data shows they can account for more than 10% of total revenue in specialty and primary care practices, and that share is growing as more practices bring diagnostics and therapy in-house to reduce patient leakage to outside facilities.
However, adding ancillary services also increases billing complexity. Unlike a standard office visit, each ancillary service often has its own CPT/HCPCS code, its own medical necessity requirements, and its own payer-specific reimbursement rules.
The Billing Challenges Unique to Ancillary Services
Ancillary services often have different billing requirements than routine E/M visits, which can create additional opportunities for claim errors and denials. Common billing issues include:
- Inconsistent coverage across payers.
Insurance plans vary in which ancillary services they cover and how they reimburse them. Before providing the service, verify the patient’s eligibility, coverage, and any applicable authorization requirements. - Complex, service-specific coding.
Ancillary services often require specific CPT or HCPCS Level II codes based on the service provided. These codes also need to be reviewed regularly as coding updates are released. For example, laboratory testing, diagnostic imaging, and DME rentals may each have different coding and billing requirements. - Technical vs. professional component splits.
Diagnostic services like imaging frequently need to be billed separately for the equipment/facility portion and the physician’s interpretation. - Medical necessity documentation.
Payers routinely deny ancillary claims when documentation doesn’t clearly justify why the service was ordered. - Prior authorization requirements.
Many diagnostic and therapeutic ancillary services require pre-certification, and missing this step is one of the most common causes of denial.
Getting these details right requires more than a general biller, it requires Medical Coding expertise that keeps pace with quarterly HCPCS and CPT updates, paired with tight Medical Billing processes that catch issues before a claim is ever submitted.
How to Bill Ancillary Services Correctly: A Step-by-Step Approach
- Verify insurance and benefits before the service is rendered.
Confirm whether the ancillary service is covered, what the patient’s cost-share is, and whether pre-authorization is required. - Document medical necessity clearly.
Every ancillary service should be tied to a specific diagnosis code that justifies why it was ordered. - Apply the correct, current codes.
Use up-to-date CPT and HCPCS Level II codes, and separate technical and professional components where applicable. - Bill the right party.
Some ancillary services are billed to insurance, others directly to the patient — get this wrong and you either lose revenue or damage patient trust. Clear, itemized Patient Billing keeps this transparent. - Track claims through to payment.
Ancillary claims can require additional follow-up when they are delayed or denied. Monitoring these claims through payment helps prevent unpaid balances from sitting in A/R too long. - Audit regularly.
Periodic internal reviews catch coding drift and missed charges before they become a pattern of denials.
Ancillary Services Billing by Practice Type
The billing requirements also vary by practice setting:
- Solo and group practices typically deal with the “in-office ancillary services” exception under Stark Law — a rule that allows physicians to bill for services like lab work and imaging performed within their own practice, provided specific supervision and billing conditions are met. Getting this structure wrong risks compliance exposure, not just denied claims.
- Hospitals typically handle large volumes of ancillary charges, including radiology, pathology, respiratory therapy, and cardiac services. These charges must be reconciled with the applicable Medicare Part A and Part B rules.
- Hospice programs must carefully distinguish which ancillary services are bundled into the hospice per-diem rate versus billed separately, a frequent source of underpayment when missed.
- SNF billing services face their own layer of complexity under the SNF Consolidated Billing rules, where most ancillary services must be billed by the facility itself rather than the outside provider performing them.
Common Mistakes That Cause Ancillary Claim Denials
- Billing an ancillary service without confirming prior authorization
- Failing to link the correct diagnosis code to justify medical necessity
- Using outdated CPT/HCPCS codes after a quarterly update
- Billing the technical and professional components incorrectly (or not splitting them at all)
- Missing the timely filing window, especially for services referred out to a third party
- Overlooking payer-specific bundling rules (e.g., SNF consolidated billing, hospice per-diem)
Each of these is preventable with the right combination of accurate Medical Coding, verified Medical Credentialing so claims aren’t rejected on enrollment issues, and a Front Office workflow that captures authorization and eligibility details at check-in, before the service is even performed.
How We Help Practices Maximize Ancillary Services Revenue
Ancillary services can add significant revenue to a practice, but only when claims are submitted correctly and followed through to payment. Our team supports the billing process from coding and claim submission through A/R follow-up, helping practices reduce avoidable denials and improve reimbursement.
From credentialing new ancillary service lines to tracking Quality Payment program performance on value-based contracts, we support the full revenue cycle behind your ancillary offerings, whether you’re a solo practice, a group practice, a hospital, a hospice, or billing under SNF rules.
Ready to stop losing revenue on ancillary services? Contact our billing team to see how much more you could be collecting.
Frequently Asked Questions
What are ancillary services in healthcare?
Ancillary services are diagnostic, therapeutic, or supportive services that complement a primary provider’s care. Examples include laboratory testing, medical imaging, physical therapy, and durable medical equipment.
What are examples of ancillary services in healthcare?
Common examples include diagnostic imaging, laboratory testing, physical and occupational therapy, mental health counseling, home health care, hospice care, and durable medical equipment.
What are the types of ancillary services in healthcare?
Ancillary services generally fall into three types: diagnostic (labs, imaging), therapeutic (physical therapy, counseling), and custodial (nursing homes, home health, hospice).
Why is billing for ancillary services more difficult than standard billing?
Ancillary services often have specific CPT or HCPCS codes, medical necessity requirements, authorization rules, and payer reimbursement guidelines. These requirements can make ancillary billing more complex than billing a standard E/M office visit.
Do ancillary services need prior authorization?
Many diagnostic and therapeutic ancillary services do require prior authorization or pre-certification, depending on the payer. Verifying this before the service is performed helps prevent denials.
