Medical Billing Glossary

CPT Codes (Current Procedural Terminology)

CPT codes are the five-digit codes maintained by the American Medical Association that describe the specific medical, surgical, and diagnostic services a provider performed during a visit. Every service billed to a payer needs a corresponding CPT code so the payer knows exactly what it’s being asked to reimburse.

Choosing the correct CPT code, and pairing it with the right level of documentation, directly determines whether a claim gets paid at the appropriate rate. Undercoding leaves revenue on the table, while overcoding invites audits, which is why accurate CPT selection is one of the most consequential parts of the billing process.

ICD-10 Codes (Diagnosis Codes)

ICD-10 codes are the standardized codes used to describe a patient’s diagnosis, symptoms, or reason for a visit. Where CPT codes describe what was done, ICD-10 codes describe why it was done, and payers use the pairing of the two to determine medical necessity.

A CPT code without a diagnosis code that supports it is one of the most common reasons a claim is denied for lack of medical necessity. Keeping diagnosis coding specific and current with each visit protects a practice from downstream denials.

HCPCS Codes (Healthcare Common Procedure Coding System)

HCPCS codes are a coding system used alongside CPT codes to describe products, supplies, and services not covered by CPT, such as durable medical equipment, ambulance transport, and certain drugs administered in a clinical setting. Level II HCPCS codes are alphanumeric, starting with a letter followed by four numbers.

Practices that bill for supplies or injectable medications in addition to office visits need to track HCPCS codes just as closely as CPT codes, since a missing or incorrect HCPCS code can cause that portion of a claim to be denied even when the visit itself is billed correctly.

Medical Coding

Medical coding is the process of translating a patient’s diagnosis, treatment, and services into the standardized CPT, ICD-10, and HCPCS codes payers use to process claims. It’s the layer that sits between clinical documentation and the billing process, and its accuracy determines how cleanly a claim moves through a payer’s system.

Coding errors, whether from outdated code sets, insufficient documentation, or simple data entry mistakes, are a leading cause of denied and delayed claims. Practices that invest in accurate, up-to-date coding tend to see meaningfully higher first-pass claim acceptance rates.

Claim Denial

A claim denial happens when a payer reviews a submitted claim and refuses to pay it, either in full or in part, because of an error, a missing piece of information, or a coverage issue. Denials are different from rejections, which occur before a claim is even processed due to a formatting or data error.

Every denial has a specific reason code attached to it, and understanding that code is the first step to correcting and resubmitting the claim. Practices that don’t systematically track denial reasons often see the same preventable errors recur month after month.

Denial Management

Denial management is the ongoing process of identifying, correcting, appealing, and preventing claim denials. It includes tracking why claims are denied, resubmitting corrected claims within payer deadlines, and identifying patterns that point to a fixable root cause, like a recurring coding error or missing authorization.

Practices without a structured denial management process often simply write off denied claims rather than appeal them, quietly losing revenue that was rightfully earned. A strong denial management program treats every denial as recoverable revenue until proven otherwise.

Clean Claim

A clean claim is one that’s submitted with all the correct information, codes, and documentation the first time, allowing it to be processed and paid without needing correction or additional information from the provider. It’s the standard every billing team aims for.

A practice’s clean claim rate, the percentage of claims that get paid on first submission, is one of the clearest indicators of how well its billing process is functioning. A low clean claim rate usually points to upstream problems in coding, documentation, or data entry that are worth investigating.

Claim Scrubbing

Claim scrubbing is the automated process of checking a claim for errors, missing information, or formatting issues before it’s submitted to a payer. Scrubbing software checks things like valid code combinations, matching patient and provider information, and payer-specific formatting rules.

Catching errors before submission rather than after a denial comes back saves significant time and speeds up the entire reimbursement cycle. Practices using a robust claim scrubbing process as part of their billing workflow generally see meaningfully higher clean claim rates.

Clearinghouse

A clearinghouse is the intermediary system that sits between a practice’s billing software and a payer, checking claims for errors and translating them into the correct electronic format before routing them to the right insurance company. Nearly all electronic claims pass through a clearinghouse rather than going directly to a payer.

Choosing the right clearinghouse, and configuring it correctly for each payer connection, affects how quickly claims are transmitted and how many get flagged for correction before they ever reach the payer. It’s a foundational, if often invisible, piece of billing infrastructure.

EOB (Explanation of Benefits)

An EOB, or Explanation of Benefits, is the document a health insurance company sends after processing a claim that shows what services were billed, what the payer allowed, what it paid, and what amount, if any, the patient is responsible for. An EOB is not a bill, though patients often mistake it for one.

For a billing team, the EOB is a key reconciliation document. It shows exactly how the payer adjudicated each line of a claim and provides the adjustment and denial codes needed to identify underpayments, appeal denials, and accurately bill the patient for their portion.

ERA (Electronic Remittance Advice)

An ERA is the electronic version of an EOB, delivered directly from the payer into a practice’s billing system or clearinghouse. It contains the same payment, adjustment, and denial information as a paper EOB but in a standardized electronic format that can be automatically posted to patient accounts.

ERA enrollment significantly reduces manual payment posting and speeds up reconciliation. Practices still relying on paper EOBs spend considerably more staff time matching payments to claims and are more likely to miss underpayments or posting errors.

EFT (Electronic Funds Transfer)

EFT is the electronic deposit of insurance payments directly into a practice’s bank account, replacing paper checks sent by mail. Most commercial payers and government programs offer or require EFT enrollment as part of the provider enrollment process.

Pairing EFT with ERA creates a nearly fully electronic payment workflow: the money arrives in the bank while the remittance detail arrives in the billing system, allowing the two to be matched and posted quickly. It’s one of the simplest ways to shorten the time between claim approval and cash in the account.

Adjudication

Adjudication is the process an insurance company uses to review a submitted claim and decide how much, if anything, it will pay. During adjudication, the payer checks the patient’s coverage, the provider’s network status, the medical necessity of the service, the accuracy of the codes, and the terms of the patient’s benefit plan.

Once adjudication is complete, the payer issues payment, a denial, or a request for additional information. Understanding where a claim sits in the adjudication process helps a billing team know whether to wait, follow up, or take corrective action.

Payment Posting

Payment posting is the process of recording insurance payments, patient payments, adjustments, and denials against the correct charges in a practice’s billing system. It sounds administrative, but accurate payment posting is what makes the rest of the revenue cycle data trustworthy.

Errors in payment posting can make accounts look unpaid when they’ve been settled, hide payer underpayments, or create incorrect patient balances. Timely, accurate posting is essential for knowing what a practice is actually owed and where follow-up is needed.

Accounts Receivable (A/R) in Medical Billing

Accounts receivable, or A/R, is the total amount of money owed to a practice for services that have already been provided but not yet paid, whether by insurance companies or patients. A/R is typically tracked by age in buckets such as 0–30, 31–60, 61–90, and 90+ days.

The older a balance gets, the harder it becomes to collect. A healthy billing operation keeps the majority of A/R in the youngest buckets and actively works older balances before payer filing deadlines or patient collection windows expire.

Modifiers in Medical Billing

Modifiers are two-character codes added to a CPT or HCPCS code to give the payer additional context about how or why a service was performed differently from the standard description. They can indicate things like multiple procedures, a distinct service, a bilateral procedure, or a service performed by an assistant surgeon.

Using the wrong modifier, or leaving one off when it’s required, is a common cause of claim denials and underpayments. Because modifier rules vary by payer and procedure, accurate use requires both coding knowledge and an understanding of each payer’s specific billing policies.

Evaluation and Management (E/M) Codes

Evaluation and Management codes are CPT codes used to bill for the cognitive work of evaluating and managing a patient’s care, including office visits, hospital visits, consultations, and other encounters. The level of E/M code selected reflects the complexity of the medical decision-making or, in some cases, the time spent with the patient.

E/M coding has undergone significant rule changes in recent years, making accurate documentation especially important. Selecting a level that isn’t supported by the medical record can lead to denials or audits, while consistently coding too low means a practice isn’t being fully reimbursed for the work its providers perform.

Medical Necessity

Medical necessity is the standard payers use to determine whether a service, procedure, or treatment was clinically appropriate and needed for a patient’s condition. A service can be performed correctly and coded accurately but still be denied if the payer doesn’t believe the diagnosis supports the service.

Establishing medical necessity starts with documentation and diagnosis coding. The clinical record needs to clearly show why the service was reasonable and necessary, and the ICD-10 code submitted on the claim needs to support that story.

Coordination of Benefits (COB)

Coordination of Benefits is the process insurance companies use to determine which plan pays first when a patient has coverage from more than one insurer. The primary payer processes the claim first, and the secondary payer may then cover some or all of the remaining balance.

Incorrect or outdated COB information is a frequent cause of claim denials. If a payer believes another insurance plan should have been billed first, it will reject the claim until the patient’s coverage order is clarified, which can create significant delays if the issue isn’t caught early.

Superbill

A superbill is a detailed document that summarizes the services a provider performed during a patient encounter, including the relevant CPT codes, ICD-10 diagnosis codes, provider information, and patient details. It serves as the bridge between the clinical visit and the billing process.

In practices that don’t code directly within an EHR, the superbill is often the billing team’s primary source for building a claim. Missing or incomplete information on the superbill creates downstream delays, making accurate charge capture at the point of care especially important.

Charge Capture

Charge capture is the process of recording every billable service, procedure, supply, and medication provided during a patient encounter so it can be coded and submitted for reimbursement. It happens at the point where clinical care becomes a financial transaction.

Missed charges are revenue that can never be recovered if no one realizes the service was provided. A reliable charge capture process ensures that everything documented in the medical record makes its way onto the claim accurately and on time.

Upcoding and Downcoding

Upcoding is the practice of billing a higher-level or more expensive service than the documentation supports, while downcoding means billing a lower-level service than what was actually performed. Upcoding can constitute fraud when done intentionally, while downcoding typically results in a practice being underpaid for legitimate work.

Both problems often stem from documentation and coding gaps rather than deliberate decisions. Regular coding audits help practices identify patterns in either direction and make sure the level of service billed consistently matches what the medical record supports.

Revenue Cycle Management (RCM)

Revenue Cycle Management, or RCM, is the end-to-end process of managing the financial side of patient care, from scheduling and insurance verification before a visit through coding, claim submission, payment posting, denial follow-up, and patient collections after the visit.

Medical billing is one part of RCM, but effective revenue cycle management looks at the entire process as a connected system. A problem at any stage, from incorrect insurance information at check-in to an unworked denial months later, can prevent a practice from collecting the revenue it earned.

Prior Authorization

Prior authorization is the approval some insurance plans require before a provider performs a specific service, procedure, test, or prescribes certain medications. The provider must submit clinical information to the payer in advance and receive authorization before the service is delivered.

Performing a service without required prior authorization is one of the most difficult denials to overturn because the payer’s approval was supposed to happen before care was provided. Verifying authorization requirements before scheduling is one of the most effective ways to prevent avoidable revenue loss.

Patient Statement

A patient statement is the bill a practice sends to a patient showing the amount they owe after insurance has processed their claim. It typically includes the services provided, insurance payments and adjustments, and the remaining patient responsibility, such as a deductible, copay, or coinsurance amount.

Clear, easy-to-understand patient statements make it more likely a patient will pay promptly and less likely they’ll call the office confused about their balance. As patient financial responsibility continues to grow, statement design and timing have become an increasingly important part of the revenue cycle.

Outsourced Medical Billing

Outsourced medical billing is the practice of hiring an external company to manage some or all of a practice’s billing and revenue cycle functions rather than handling them entirely with in-house staff. Services can include coding, claim submission, denial management, payment posting, A/R follow-up, patient billing, and reporting.

For small and mid-sized practices, outsourcing can reduce the risk of relying on a single in-house biller and provide access to a broader team with payer-specific and specialty-specific expertise. The value of an outsourced partner depends heavily on how actively they manage denials, follow up on A/R, communicate with the practice, and report on financial performance.

DME Billing (Durable Medical Equipment)

DME billing is the specialized process of submitting claims for durable medical equipment such as wheelchairs, oxygen equipment, braces, and other reusable medical supplies prescribed for a patient’s use. DME claims follow a distinct set of Medicare and commercial payer rules, including specific HCPCS codes, documentation standards, and supplier enrollment requirements.

Because DME billing has strict medical necessity and documentation requirements, even small gaps in a physician’s order or proof of delivery can lead to a denial. Practices and suppliers that bill DME need billing workflows built specifically around these requirements rather than treating equipment claims like standard professional services.