Medical Billing Terms C: Coordination of Benefits, CMS-1500 and Coinsurance

Coordination of benefits (COB) is how payers decide which plan pays first when a patient has more than one. This page defines COB and the terms from CMS-1500 to conversion factor, including CMS-855I, COBRA, coinsurance and contracted rate. Each entry gives a plain definition, why it matters, an example, and an official source. MCM South Medical Billing Service, LLC works only in mental and behavioral health billing.

Last reviewed: October 10, 2026Sources linked at each term

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Billing Terms Glossary slide, Terms C: Coordination of Benefits - MCM South Medical Billing Service, LLC

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On this page (22 terms)

CMS-1500
CMS-855
CMS-855I
CMS-855R
COBRA
Code Crosswalk
Coding Denial
Coinsurance
Collaborative Care Model (CoCM)
Collections
Community Mental Health Center (CMHC)
Companion Guide
Compliance Officer
Compliance Program
Concurrent Review
Confidential Communications Request
Connecticut Behavioral Health Partnership
Continuity of Care
Contracted Rate
Contractual Adjustment
Conversion Factor
Coordination of Benefits (COB)

How to use these Coordination of Benefits definitions

Use this page as a quick reference for Coordination of Benefits, from CMS-1500 to Coordination of Benefits. Each entry gives a plain definition, why it matters to a mental health practice, and an official source. When a rule changes by payer or state, the entry says so, so confirm Coordination of Benefits details with the payer before you bill.

Checklist: put the coordination of benefits definitions to work

Check the coordination of benefits entries above before you send a claim that depends on them.
Share this coordination of benefits page with front-desk and billing staff so everyone works from the same definitions.
When a payer letter mentions coordination of benefits, find the matching entry and note the date you checked it.
Keep your coordination of benefits notes next to your payer contracts, because a contract can define a term differently.

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CMS-1500

General (all payers)

Also called CMS-1500 form; HCFA-1500; professional claim form

Definition: The standard paper claim form for professional services, maintained by the NUCC, whose electronic equivalent is the 837P.
Why it matters: Most outpatient therapy and psychiatry claims use it or its 837P equivalent.
Illustrative example: A practice mails a CMS-1500 to a payer that does not accept electronic claims.

Reference sourceNUCCchecked 10/9/26

CategoriesClaims Processing EDI & Clearinghouse Terms

CMS-855

General (all payers)

Also called CMS-855I; CMS-855B; CMS-855R; Medicare enrollment application

Definition: The family of Medicare enrollment application forms. Different versions cover individual practitioners, organizations, and reassignment.
Why it matters: Choosing the wrong form delays enrollment.
Illustrative example: An individual clinician files the CMS-855I to enroll in Medicare.

Reference sourceCMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesCredentialing & Enrollment Medicare & Medicaid Terms

CMS-855I

Medicare

Also called 855I; Medicare enrollment application individual practitioner; CMS 855I form

Definition: CMS-855I is the Medicare enrollment application for individual physicians and non-physician practitioners who want to enroll or change their enrollment information.
Why it matters: Errors or missing information delay enrollment. Many enroll or update through PECOS online. Use the correct form for the enrollment action.
Illustrative example: A newly licensed clinician completes the 855I in PECOS to enroll in Medicare.

Reference sourceCMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesCredentialing & Enrollment Medicare & Medicaid Terms

CMS-855R

Medicare

Also called 855R; Medicare reassignment of benefits form; CMS 855R form

Definition: CMS-855R is the Medicare form used to reassign the right to receive Medicare payment from an individual practitioner to another eligible entity, such as a group practice.
Why it matters: A clinician joining a group usually needs a reassignment on file before the group can be paid for their services. Keep the group and the clinician's records aligned.
Illustrative example: A therapist joins a group, and both the therapist and the group complete an 855R so the group can bill for her Medicare services.

Reference sourceCMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesCredentialing & Enrollment Medicare & Medicaid Terms

COBRA

General (all payers)

Also called Consolidated Omnibus Budget Reconciliation Act; COBRA continuation coverage

Definition: A federal law that lets some people keep employer group health coverage for a limited time after certain events, such as job loss, usually by paying the full premium.
Why it matters: Patients on COBRA may have retroactive terminations if premiums are not paid, causing eligibility denials.
Illustrative example: A patient elects COBRA after leaving a job and the practice re-verifies coverage.

Reference sourceU.S. Department of Labor, EBSAchecked 10/9/26

CategoriesEligibility & Benefits

Code Crosswalk

General (all payers)

Also called CPT crosswalk; code mapping

Definition: A table that maps one code set or code to another, such as a payer's local code to a standard CPT or HCPCS code.
Why it matters: Useful when payers or state Medicaid programs use local codes.
Illustrative example: A billing team maps a state code to a CPT code.

Reference sourceCMS (Centers for Medicare & Medicaid Services)CMS HCPCSchecked 10/9/26

CategoriesClaims Processing EHR & Healthcare Technology Terms

Coding Denial

General (all payers)

Also called invalid code denial; bundling denial

Definition: A denial because a code, modifier, diagnosis, or code combination is invalid or not payable under payer edits.
Why it matters: Fixed by correcting the code or appealing with documentation.
Illustrative example: A claim denies for a diagnosis that does not support the CPT code.

Reference sourceCMS (Centers for Medicare & Medicaid Services)CMS National Correct Coding Initiative (NCCI)checked 10/9/26

CategoriesDenials & Appeals Claims Processing

Coinsurance

General (all payers)

Also called patient coinsurance; percentage share

Definition: The percentage of the allowed amount a member pays for a covered service after meeting the deductible.
Why it matters: Practices must calculate it on the allowed amount, not the billed charge.
Illustrative example: A plan pays 80% and the member pays 20% coinsurance on the allowed amount.

Reference sourceCMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesPatient Financial Responsibility Terms Eligibility & Benefits

Collaborative Care Model (CoCM)

General (all payers)

Also called CoCM; collaborative care; psychiatric collaborative care; 99492; 99493; 99494

Definition: A team-based approach that integrates behavioral health into primary care with a care manager and psychiatric consultant, billed with monthly codes.
Why it matters: Requires specific staffing, documentation, and consent, and payer coverage varies.
Illustrative example: A primary care practice bills CoCM codes monthly with time tracking.

Reference sourceCMS (Centers for Medicare & Medicaid Services)CMS Medicare Learning Network (MLN)checked 10/9/26

CategoriesBehavioral Health Specific Terms Value-Based Care Terminology

Collections

General (all payers)

Also called collection agency; patient collections

Definition: Efforts, sometimes through an outside agency, to recover unpaid patient balances.
Why it matters: Requires compliance with debt collection laws and privacy rules.
Illustrative example: A practice sends a past-due balance to an agency after notices.

Reference sourceHFMAchecked 10/9/26

CategoriesPatient Financial Responsibility Terms Revenue Cycle Metrics

Community Mental Health Center (CMHC)

General (all payers)

Also called CMHC

Definition: A community-based provider of mental health services, with special rules under Medicare and Medicaid.
Why it matters: Payment and enrollment rules differ from private practice.
Illustrative example: A CMHC bills Medicaid under its state program.

Reference sourceCMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesBehavioral Health Specific Terms Medicare & Medicaid Terms

Companion Guide

General (all payers)

Also called payer companion guide; EDI companion guide

Definition: A payer's document that explains its specific requirements for standard transactions within the HIPAA formats.
Why it matters: Explains payer-specific data requirements that cause rejections.
Illustrative example: A biller reads the companion guide before enrolling.

Reference sourceX12checked 10/9/26

CategoriesEDI & Clearinghouse Terms

Compliance Officer

General (all payers)

Also called privacy officer; security officer

Definition: A person responsible for overseeing compliance policies, training, and investigations in an organization.
Why it matters: A named person should own compliance duties even in small practices.
Illustrative example: A practice names an owner as compliance and privacy officer.

Reference sourceHHS Office of Inspector General (OIG)checked 10/9/26

CategoriesAudits & Compliance

Compliance Program

General (all payers)

Also called corporate compliance plan; compliance plan

Definition: A set of written policies, training, auditing, and reporting processes that a practice uses to prevent and detect billing and privacy violations.
Why it matters: OIG guidance describes elements of an effective plan.
Illustrative example: A group adopts written policies, annual training, and a compliance contact.

Reference sourceHHS Office of Inspector General (OIG)checked 10/9/26

CategoriesAudits & Compliance

Concurrent Review

General (all payers)

Also called continued stay review; concurrent authorization

Definition: A review during ongoing treatment that decides whether more sessions or days are authorized.
Why it matters: Missing a concurrent review can end authorization.
Illustrative example: A payer reviews an intensive outpatient program every set number of days.

Reference sourceURACchecked 10/9/26

CategoriesPrior Authorization Terminology

Confidential Communications Request

General (all payers)

Also called HIPAA confidential communications; alternative contact request; request to send EOB elsewhere

Definition: A confidential communications request is a patient's request under HIPAA to receive communications about their health information by another means or at another location, such as a different address, phone number, or email.
Why it matters: For minors and for adults on someone else's plan, it can keep billing notices and explanations of benefits from reaching the policyholder. Providers must accommodate reasonable requests. Health plans must accommodate reasonable requests when the person says that disclosure could endanger them. Record the request and tell the billing team.
Illustrative example: A young adult on a parent's plan asks that appointment reminders go only to their own phone, so the practice records the request in the chart.

Reference sourceHHS (U.S. Department of Health and Human Services)HHS Office for Civil Rights (OCR)checked 10/9/26

CategoriesAudits & Compliance Patient Financial Responsibility Terms

Connecticut Behavioral Health Partnership

Medicaid (state-specific)

Also called CT BHP; Connecticut Medicaid behavioral health

Definition: A Connecticut program that manages Medicaid behavioral health services through an administrative services organization.
Why it matters: Connecticut is a served state; behavioral health may be managed outside standard plans.
Illustrative example: A Connecticut provider enrolls with the program's administrator.

Reference sourceMedicaid.govchecked 10/9/26

CategoriesMedicare & Medicaid Terms Behavioral Health Specific Terms

Continuity of Care

General (all payers)

Also called transition of care; transitional care period

Definition: A period in which a member can keep seeing a provider who has left the network, at in-network cost sharing, under plan or state rules.
Why it matters: It affects how claims from a newly out-of-network clinician are processed for a limited time.
Illustrative example: A member in active treatment keeps seeing a therapist during a payer-defined transition period.

Reference sourceCMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesContracting & Network Management Eligibility & Benefits

Contracted Rate

General (all payers)

Also called negotiated rate; contract rate; in-network rate

Definition: The amount a payer has agreed to pay a participating provider for a service under the contract.
Why it matters: Sets expected payment and helps spot underpayments.
Illustrative example: A payer's contract lists a rate for 90837; the practice compares it to each remittance.

Reference sourceCMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesContracting & Network Management Payment & Reimbursement

Contractual Adjustment

General (all payers)

Also called contractual write-off; CO adjustment

Definition: The portion of the billed charge a participating provider must write off because it exceeds the contracted allowed amount.
Why it matters: It is not collectible from the patient and must be posted correctly to keep A/R accurate.
Illustrative example: The ERA shows a $50 contractual adjustment with group code CO.

Reference sourceCMS (Centers for Medicare & Medicaid Services)X12checked 10/9/26

CategoriesPayment & Reimbursement Revenue Cycle Metrics

Conversion Factor

General (all payers)

Also called CF; Medicare conversion factor

Definition: The dollar amount that multiplies total RVUs to set the Medicare payment for a service.
Why it matters: Changes to it move Medicare payment for every service, and many contracts key off it.
Illustrative example: A rule finalizes a new conversion factor for the calendar year.

Reference sourceCMS (Centers for Medicare & Medicaid Services)CMS Physician Fee Schedulechecked 10/9/26

CategoriesPayment & Reimbursement

Coordination of Benefits (COB)

General (all payers)

Also called COB; other insurance; dual coverage

Definition: The process that determines which plan pays first and how much each pays when a patient has more than one plan, so total payment does not exceed allowed limits.
Why it matters: COB errors are a leading cause of denials and delayed payments.
Illustrative example: A payer denies a claim pending a COB questionnaire response from the patient.

Reference sourceCMS (Centers for Medicare & Medicaid Services)checked 10/9/26

CategoriesEligibility & Benefits Claims Processing

Quick answer: Coordination of Benefits

What is coordination of benefits?

Coordination of Benefits (COB) is the process that determines which plan pays first and how much each pays when a patient has more than one plan, so total payment does not exceed allowed limits. COB errors are a leading cause of denials and delayed payments.

Frequently asked questions: Coordination of Benefits

What is the CMS-1500 form?

CMS-1500 is the standard paper claim form for professional services, maintained by the NUCC, whose electronic equivalent is the 837P. Most outpatient therapy and psychiatry claims use it or its 837P equivalent.

What is coinsurance?

Coinsurance is the percentage of the allowed amount a member pays for a covered service after meeting the deductible. Practices must calculate it on the allowed amount, not the billed charge.

What is CMS-855I?

CMS-855I is the Medicare enrollment application for individual physicians and non-physician practitioners who want to enroll or change their enrollment information. Errors or missing information delay enrollment.

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Where MCM South works

MCM South serves psychotherapists and psychiatrists in ten states: Georgia, Massachusetts, Connecticut, Texas, Florida, New York, Colorado, Tennessee, North Carolina and Illinois.

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