Medical Billing Systems: 3 Types, HB vs PB, Software and Payment Models

A medical billing system is the set of software and processes a healthcare organization uses to turn patient care into claims, payments and patient bills. There are three types of medical billing systems: closed (data stays inside one practice), open (data is shared across providers and systems) and isolated (data is shared selectively within a defined network). Hospitals and physicians also bill differently. Hospital billing (HB) uses the UB-04 form, and professional billing (PB) uses the CMS-1500.

Choosing the right billing system affects how fast you get paid, how many claims are denied and how much staff time billing takes. At AffinityCore, we work in all three system types every day, across independent practices, multi-site groups and hospitals. This guide explains each system, the billing and payment models behind it, and the software features that keep claims clean.

What Is a Medical Billing System?

A medical billing system is the combination of software, people and workflows that records the services a provider delivers, codes them, sends claims to payers, posts payments and bills patients for their share. In healthcare, “billing system” can mean the software (a practice management or hospital billing platform) or the overall model for how data and claims flow between organizations.

Every healthcare billing system, whether it serves a solo practice or a 500-bed hospital, moves a claim through the same core steps:

1. Patient registration: demographics and insurance details are captured.
2. Eligibility and authorization: coverage is verified and prior authorizations are obtained.
3. Coding: diagnoses are coded in ICD-10-CM and services in CPT/HCPCS (or ICD-10-PCS for inpatient procedures).
4. Charge entry: coded services, units and fees are entered into the billing system.
5. Claim scrubbing: software edits check the claim for errors before it is sent.
6. Claim submission: the claim goes to the payer, usually through a clearinghouse as an 837 file.
7. Payment posting: the payer’s remittance (835/ERA) is posted, and denials are flagged.
8. Denial management and AR follow-up: unpaid and denied claims are worked and appealed.
9. Patient billing: the patient receives a statement for any remaining balance.

The type of billing system you use decides how smoothly data passes between these steps, and between you and other providers.

What Are the 3 Types of Billing Systems in Healthcare?

The three types of medical billing systems are closed, open and isolated. They differ in one thing: how much patient and billing data can be shared outside the organization that created it.

1. Closed medical billing system

A closed system keeps all patient and billing data inside one practice or facility. Records created there stay there. Small independent practices that use a single EHR and billing tool typically run closed systems.

• Pros: strong privacy control, simple workflows, lower cost.
• Cons: hard to coordinate care or billing with outside providers, and records must be re-entered when patients are referred elsewhere.

2. Open medical billing system

An open system is built for interoperability. Patient and billing data move between providers, labs, hospitals and payers through connected EHRs and health information exchanges (HIEs). Large health systems and integrated networks typically run open systems.

• Pros: less duplicate data entry, better care coordination, more accurate billing across departments.
• Cons: higher cost, more complex security and HIPAA oversight, and dependence on integration standards such as HL7 and FHIR.

3. Isolated (partially open) medical billing system

An isolated system sits between the two. Data is shared selectively within a defined group, such as a hospital and its affiliated clinics, while staying closed to everyone else. Patients may also see their records through a portal.

• Pros: balances privacy and coordination, and suits multi-location groups.
• Cons: sharing rules need careful management, and the network’s boundaries can still create data gaps.

Closed vs open vs isolated: comparison

Factor	Closed	Isolated	Open
Data sharing	None outside the practice	Within a defined network	Across providers, labs, payers
Typical user	Solo or small practice	Hospital group, multi-site practice	Health system, integrated network
Cost	Lowest	Moderate	Highest
Privacy control	Highest	High	Requires strongest safeguards
Care coordination	Limited	Good within network	Best
Duplicate data entry	Most	Some	Least

Many modern practices also use a cloud-based billing system. This describes where the software runs, not how data is shared, so a cloud system can be closed, isolated or open.

Hospital vs Physician Billing: What Is HB vs PB?

HB (hospital billing) bills the facility’s costs: the room, nursing, equipment, supplies and drugs. PB (professional billing) bills the physician’s or clinician’s own work. One hospital visit often produces two bills, for example a facility claim for the ER and a professional claim for the emergency physician.

Factor	Hospital billing (HB)	Physician / professional billing (PB)
Also called	Institutional or facility billing	Professional billing
Claim form	UB-04 (CMS-1450)	CMS-1500
Electronic format	837I	837P
Who bills	Hospitals, SNFs, home health, hospice, ASCs (some payers)	Physicians, NPs, PAs, therapists, DME suppliers
Codes used	Revenue codes, ICD-10-PCS (inpatient), CPT/HCPCS (outpatient), type of bill	CPT/HCPCS, modifiers, place of service
Medicare payment	DRGs (inpatient), APCs (outpatient)	Physician Fee Schedule (RVUs)

Types of providers in medical billing

There are two main types: institutional providers, which bill on the UB-04 (hospitals, skilled nursing facilities, home health agencies, hospices), and professional providers, which bill on the CMS-1500 (physicians, non-physician practitioners and therapists). Suppliers of DME and medical equipment also bill on the CMS-1500, to the DME contractor.

What is the type of bill (TOB) code?

The type of bill is a 4-digit code in Form Locator 4 of the UB-04. It tells the payer what kind of facility sent the claim, the type of care and where the claim sits in the billing sequence. The first digit is a leading zero, the second is the facility type, the third is the care type and the fourth is the frequency.

Bill type	Meaning
0111	Hospital inpatient, admit through discharge
0131	Hospital outpatient, admit through discharge
0211	Skilled nursing facility inpatient
0321	Home health under a plan of treatment
0711	Rural health clinic
0811	Hospice (non-hospital based)
0851	Critical access hospital outpatient
xxx7 / xxx8	Replacement of a prior claim / void of a prior claim

What is type of service in medical billing?

Type of service (TOS) is a one-character code Medicare uses to classify each service, for example 1 = medical care, 2 = surgery, 4 = diagnostic radiology, 5 = diagnostic lab and 7 = anesthesia. Medicare assigns TOS from the HCPCS code, so it isn’t entered on today’s CMS-1500. Don’t confuse it with place of service (POS), the 2-digit code for where care happened, such as 11 office, 22 on-campus outpatient hospital or 23 emergency room.

Types of Medical Billing Software

Medical billing software falls into three main types, defined by what it connects to and where it runs.

Type	What it is	Best for
Standalone billing software	Billing and claims only; clinical data comes from a separate EHR	Practices that want to keep their EHR and upgrade billing
Integrated PM/EHR suite	Scheduling, clinical notes, coding and billing in one platform	Practices that want one login and no re-entry between systems
Hospital billing / enterprise RCM platform	Institutional billing with revenue codes, chargemaster, DRG/APC grouping	Hospitals and health systems

Each type can be cloud-based (hosted by the vendor, accessed in a browser) or on-premise (installed on the practice’s own servers). Cloud systems now dominate in physician practices because updates, backups and security patches are handled by the vendor.

Must-have medical billing features

• Real-time eligibility checks before the visit
• Claim scrubber with payer-specific edits
• Clearinghouse integration for 837 submission and 835 remittance
• Electronic remittance (ERA) and auto-posting
• Denial tracking by CARC/RARC code, payer and provider
• AR aging reports in 0–30, 31–60, 61–90 and 90+ day buckets
• Patient statements and online payments, including a patient portal
• HIPAA safeguards: role-based access, audit logs and encryption

What edits does insurance billing software run?

A claim scrubber runs edits that stop errors before payers see them. Two of the most important are:

1. NCCI procedure-to-procedure (PTP) edits: flag code pairs that shouldn’t be billed together on the same day for the same patient, unless a modifier such as 59 or XS supports a distinct service.
2. Medically Unlikely Edits (MUEs): flag units above the maximum CMS considers plausible for one patient on one day, for example too many units of a timed therapy code.

Other common edits check diagnosis-to-procedure medical necessity (against LCDs and NCDs), missing or invalid data (NPI, member ID, date of birth), age and gender conflicts, and timely filing limits.

Healthcare Payment Methodologies and Reimbursement Systems

A billing system has to support the way each payer pays. Six payment methodologies cover most US healthcare reimbursement:

Payment method	How it pays	Common examples
Fee-for-service (FFS)	A set amount for each service billed	Commercial plans, Medicare Physician Fee Schedule
Capitation	A fixed amount per member per month, whatever services are used	HMOs, Medicare Advantage provider contracts
DRG (inpatient prospective payment)	One payment per inpatient stay, based on the diagnosis-related group	Medicare IPPS (MS-DRGs)
APC (outpatient prospective payment)	Payment per outpatient service group	Medicare OPPS for hospital outpatient departments
Bundled / episode payment	One payment for all care in an episode, such as a joint replacement	CMS bundled payment models, commercial bundles
Value-based payment	Payment adjusted for quality and cost results	ACOs, MIPS, shared savings contracts

Hospitals mostly work with DRGs and APCs. Physician practices mostly work with fee-for-service and, more and more, value-based adjustments. A billing system that can’t model your contracts can’t tell you when a payer underpays.

Medical billing financial class list

A financial class groups patient accounts by who pays, so billing teams can apply the right rules and track AR by payer type. A typical list:

• Medicare (traditional)
• Medicare Advantage
• Medicaid and Medicaid managed care
• Commercial / private insurance
• Managed care (HMO, PPO, EPO)
• TRICARE and VA (CHAMPVA, Community Care)
• Workers’ compensation
• Auto / liability (motor vehicle accident)
• Self-pay (uninsured or patient responsibility)
• Charity / financial assistance

In-House Billing Department vs Outsourced Medical Billing

The software is only half of a billing system; the other half is the people running it. Practices either staff an in-house billing department or outsource billing to a revenue cycle partner.

Factor	In-house billing department	Outsourced billing partner
Cost model	Salaries, benefits, software and training	Usually a percentage of collections
Expertise	Depends on a few staff members	Certified coders and specialty teams
Coverage	Gaps during turnover, illness or leave	Continuous team coverage
Payer rule updates	Staff must track changes themselves	Partner tracks rules across payers
Control	Full, day-to-day	Shared, through reporting and KPIs
Scalability	Hiring needed to grow	Scales with volume

In-house billing works well when you have experienced staff and stable volume. Outsourcing makes sense when denials are rising, AR is aging past 90 days, or one person holds all the billing knowledge. See our full in-house vs outsourced medical billing comparison.

How AffinityCore Makes Any Medical Billing System Work Harder

Whatever billing system you run, closed, open or isolated, standalone or integrated, AffinityCore works inside it. We don’t ask you to switch software. We fix the process around it.

• End-to-end revenue cycle management: registration, eligibility, coding, charge entry, claims, payment posting and patient billing, handled by one team.
• Hospital and professional billing: UB-04 and CMS-1500 expertise, including correct type of bill, revenue codes, place of service and modifiers.
• Certified coding and charge entry: AAPC-certified coders, with NCCI and MUE checks built into every claim.
• Denial management and AR recovery: root-cause fixes so the same denial doesn’t come back.
• Real-time reporting: dashboards for clean-claim rate, denial rate, days in AR and collections by financial class.

Not sure your billing system is collecting everything you’re owed? Request a free revenue analysis from AffinityCore. We’ll review your claims, denials and AR and show you exactly where revenue is leaking.

Frequently Asked Questions

What are the 3 types of billing systems in healthcare?

The three types are closed, open and isolated. A closed system keeps data inside one practice. An open system shares data across providers and payers. An isolated system shares data only within a defined network, such as a hospital and its clinics.

What is the difference between HB and PB billing?

HB (hospital billing) bills a facility’s costs on the UB-04 form. PB (professional billing) bills a clinician’s services on the CMS-1500. One hospital visit can produce both an HB claim and a PB claim.

What is a bill type in medical billing?

A bill type is a 4-digit code in Form Locator 4 of the UB-04 that identifies the facility type, the type of care and the claim frequency. For example, 0111 is a hospital inpatient claim covering admission through discharge.

What are the main types of medical billing software?

The main types are standalone billing software, integrated practice management and EHR suites, and enterprise hospital billing platforms. Any of them can be cloud-based or installed on-premise.

What are two edits associated with insurance billing software?

Two key edits are NCCI procedure-to-procedure edits, which flag code pairs that shouldn’t be billed together, and Medically Unlikely Edits (MUEs), which flag units above the daily maximum CMS allows.

What are the main healthcare payment methodologies?

The main methods are fee-for-service, capitation, DRG-based inpatient payment, APC-based outpatient payment, bundled episode payments and value-based payment tied to quality and cost results.