Medical billing glossary

A clean claim is a claim that passes payer adjudication and is paid on first submission, without rejection, denial or a request for additional information. Clean claim rate — the percentage of claims meeting that standard — is the most direct measure of whether a billing operation is working.

Claim scrubbing is the automated review of a claim before submission, checking it against payer rules, code edits and formatting requirements to catch errors that would cause a rejection or denial. It runs after coding and before transmission, and it is the cheapest possible point of correction.

A clearinghouse is an intermediary that receives claims from providers, validates and reformats them into each payer's required electronic standard, and routes them onward. It also returns acknowledgements, rejections and electronic remittance advice, acting as the single connection point to hundreds of payers.

The EDI 837 is the HIPAA-mandated electronic format for submitting healthcare claims. The 837P variant carries professional claims, 837I carries institutional claims, and 837D carries dental. It is the electronic equivalent of a CMS-1500 or UB-04 paper form.

An electronic remittance advice, transmitted as an X12 835 file, is the payer's electronic explanation of how a claim was adjudicated. It reports what was allowed, what was paid, what was adjusted and why — using CARC and RARC codes — and it drives automated payment posting.

The CMS-1500 is the standard paper claim form used by physicians and non-institutional providers to bill Medicare, Medicaid and most commercial payers. It is maintained by the National Uniform Claim Committee, and its electronic equivalent is the EDI 837P transaction.

A superbill is an itemized record of the services a provider delivered during a visit, listing diagnosis and procedure codes, provider details and charges. It is not a claim: it is the source document a biller converts into a claim, or that a patient submits to seek out-of-network reimbursement.

A CPT code is a five-character code maintained by the American Medical Association that identifies the procedure or service a provider performed. CPT answers what was done; ICD-10-CM answers why. Together they establish medical necessity, and a mismatch between them is a leading denial cause.

ICD-10-CM is the diagnosis code set used in the United States to report the clinical reason for a service. Codes run three to seven characters, and the later characters carry specificity — laterality, encounter type, episode — that payers increasingly require before they will accept medical necessity.

HCPCS Level II is a CMS-maintained code set covering products, supplies and services not included in CPT — durable medical equipment, prosthetics, ambulance services, and drugs administered in a clinical setting. Level I of HCPCS is CPT itself.

A modifier is a two-character suffix appended to a CPT or HCPCS code that alters its meaning without changing the code itself — signalling that a service was distinct, bilateral, repeated, reduced or performed by a specific provider role. Modifiers are how correct coding survives contact with bundling edits.

Evaluation and management coding assigns a level of service to a patient encounter based on either medical decision making or total time spent on the date of the encounter. Since the 2021 guideline revision, history and exam no longer determine the level for office visits.

National Correct Coding Initiative edits are CMS-published rules preventing improper code pairings. Procedure-to-procedure edits stop two codes being billed together when one is a component of the other; medically unlikely edits cap the units of a code reportable for one patient on one day.

A denial is a claim the payer adjudicated and refused to pay. It differs from a rejection, which never entered adjudication. That distinction determines your remedy: a rejected claim is corrected and resubmitted, while a denied claim must be appealed within the payer's deadline.

A rejection is a claim stopped before adjudication — by the clearinghouse or the payer's intake system — for a format, data or eligibility error. Because it never entered adjudication, it carries no appeal rights and does not appear in payer claim status. It must be corrected and resubmitted.

A claim adjustment reason code explains why a payer adjusted or denied a payment. Maintained by X12, each CARC carries a group code — CO for contractual obligation, PR for patient responsibility, OA for other adjustment — which determines whether the balance may be billed to the patient.

A remittance advice remark code supplements a CARC with the specific reason behind an adjustment. Where a CARC says information is missing, the RARC says which information. Reading the RARC is usually what determines whether a denial is correctable, appealable, or genuinely final.

An appeal is a formal request that a payer reconsider a denied claim, supported by documentation addressing the stated denial reason. Commercial payers typically allow 90 to 180 days from the remittance date; Medicare provides five escalating levels beginning with redetermination within 120 days.

Timely filing is the deadline by which a payer must receive a claim. Limits commonly range from 90 days to one year from the date of service, vary by payer and contract, and are shorter for secondary claims. A claim denied for timely filing is generally unappealable and unbillable to the patient.

Medical necessity is a payer's determination that a service was appropriate for the patient's condition under its coverage policy. It is established by the pairing of diagnosis and procedure codes and supported by the documentation — which means a medically necessary service can still be denied if the coding does not demonstrate it.

Revenue cycle management is the end-to-end financial process a healthcare practice runs from the moment a patient schedules an appointment until the balance for that visit is fully paid. It covers eligibility verification, coding, claim submission, payer follow-up, denial appeals, patient billing and reporting.

Charge capture is the process of recording every billable service a provider delivered so it reaches a claim. Services documented in the chart but never converted into a charge are revenue lost permanently — no denial appears, no report flags it, and nothing prompts anyone to look.

Payment posting is the recording of payer and patient payments against the correct claims and service lines, including contractual adjustments, write-offs and patient responsibility. Done well it reconciles to the bank deposit; done poorly it corrupts every AR and denial report downstream.

Undercoding is billing a lower-level or less specific code than the documentation supports. It produces no denials, triggers no alerts and appears nowhere in a standard revenue report — which makes it the least visible and most persistent form of revenue leakage in a physician practice.

Days in accounts receivable measures the average time between billing a service and collecting payment. It is calculated as total accounts receivable divided by average daily charges. It is the single best summary indicator of revenue cycle health, because every upstream failure eventually shows up in it.

Denial rate is the percentage of submitted claims a payer denies, usually measured on first submission. MGMA data puts single-specialty physician practices at roughly 8%; Kodiak Solutions reports 11.81% for hospitals and health systems in 2024. Above 10% is where practices generally start losing material revenue.

Net collection rate is payments received divided by the amount you were contractually entitled to collect, after removing contractual adjustments. It answers the question gross collection rate cannot: of the money you actually had a right to, how much did you get?

A contractual adjustment is the difference between a provider's billed charge and the contracted allowed amount with that payer. It is not a loss and not collectible from the patient — it is the discount agreed to in the contract, and it must be recorded separately from write-offs.

An underpayment is a claim paid below the contracted allowed amount. Unlike a denial it produces no alert, posts cleanly, and closes the claim — which is why systematic underpayment can run for years without anyone noticing. Detection requires comparing every payment against a loaded fee schedule.

Prior authorization is a payer requirement that a service be approved before it is delivered. Without it, the claim is denied regardless of medical necessity, and in most contracts the balance cannot be billed to the patient — the practice absorbs it entirely.

The allowed amount is the maximum a payer recognizes for a covered service under its contract with the provider. It sets the ceiling on total payment — payer portion plus patient responsibility — and the difference between billed charge and allowed amount becomes a contractual adjustment.

Eligibility verification confirms a patient's active coverage, benefits, deductible status, copay, coinsurance and authorization requirements before the service is delivered. It runs electronically through the X12 270 inquiry and 271 response, and it prevents the largest single category of denials.

Coordination of benefits determines which payer is primary when a patient has more than one plan, and in what order the others pay. Billing the wrong payer first produces a denial that cannot be fixed by resubmission alone — the payers' own COB records must be corrected first.

Patient responsibility is the portion of an allowed amount the patient owes: copay, coinsurance, deductible and non-covered charges. It is identified on the remittance by PR group codes, and it has become materially harder to collect as high-deductible plans have grown.

Out-of-network describes a provider with no contract with a patient's payer. Without a contracted allowed amount the payer applies its own reimbursement methodology, patient cost-sharing is higher, and federal No Surprises Act protections restrict what may be balance-billed in emergency and certain facility-based situations.

Upcoding is billing a higher-paying code than the documented service supports. It is a False Claims Act exposure regardless of intent, and it is detected statistically — payers profile a provider's code distribution against peers in the same specialty, so a skewed pattern surfaces without any single claim being reviewed.

Credentialing is the verification of a provider's qualifications by a payer, and enrollment is the resulting contract that permits billing under that plan. The process commonly takes 90 to 180 days, and claims for services delivered before the effective date are generally not payable.

A National Provider Identifier is the 10-digit identifier required on all HIPAA standard transactions. Type 1 identifies an individual provider; Type 2 identifies an organization. Both usually appear on a claim — the rendering provider as Type 1, the billing entity as Type 2.

HIPAA is the federal law governing the privacy and security of protected health information. For billing it establishes three obligations: the standard electronic transaction formats, the Privacy Rule limiting use and disclosure of PHI, and the Security Rule requiring safeguards for electronic PHI.

A Business Associate Agreement is the HIPAA-required contract between a covered entity and a vendor handling protected health information on its behalf. It defines permitted uses, mandates safeguards, sets breach notification obligations, and governs return or destruction of PHI when the relationship ends.

The minimum necessary standard requires that uses and disclosures of protected health information be limited to the least amount needed to accomplish the purpose. It applies directly to billing operations, where the temptation to move whole charts rather than the relevant documentation is constant.