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Helpful terms/glossary

Health insurance terms can be confusing. This glossary offers simple, clear definitions to help you navigate your coverage with more confidence.

Index

Durable Medical Equipment (DME)

DME, as defined by Original Medicare, is reusable medical equipment.1

 

DME equipment under Medicare guidelines must meet these criteria2:

  • Durable (can withstand repeated use)2
  • Used for a medical reason2
  • Typically only useful to someone who is sick or injured2
  • Used in your home2
  • Expected to last at least 3 years2

(Most private insurance companies follow Medicare guidelines. Please refer to your specific insurance plan for details.)

 

List of Medicare covered DME2

Medicare DME booklet1

 

Durable Medical Supplier

A durable medical supplier is any company selling medical equipment used in the home to aid in a better quality of living.

Durable medical suppliers offer DME equipment and medical supplies such as catheters, wheelchairs, shower chairs, canes, incontinence products, colostomy products, etc.

When you require a piece of DME equipment or specific medical supplies, you may have a choice of many different suppliers, but it is important to choose one that is in your insurer’s network (or participating in Medicare if applicable).2,3

Explanation of Benefits (EOB)

An EOB shows you your total charges for your visit. An EOB is not a bill. It helps you, the patient, understand how much your health plan covers, and what you’ll pay when you get a bill from your provider.4

The explanation of benefits includes information about:

  • You (the patient)
  • Your health plan
  • Who provided your care and when it was approved
  • A reference number called the claim number
  • The person who gets reimbursed for overpayments called the payee4

Detailed explanation of how to read your EOB4

Deductible

What the patient pays annually for health services before the patient’s insurance company starts to pay.5

Detailed explanation of Medicare deductible5

 
Co-insurance

The percentage of the cost of a covered healthcare service or prescription drug the patient pays after the deductible has been met.5

Full definition of Medicare co-insurance5

 
Co-payment

A co-pay is a set dollar amount a patient pays for a covered healthcare service at the time they receive care or pick up a prescription drug.5

Full definition of Medicare co-payments5

 
Out-of-pocket maximum

The most the patient has to pay for covered services in a plan year. After a patient spends this amount on deductibles, copays, and coinsurance - a patient’s health care provider will pay 100% of allowable in-network costs.3,6

Full understanding of Medicare out-of-pocket costs6

 
Premium

A health insurance premium is the cost of keeping a patient’s health insurance plan active. It is a monthly fee you pay for your health insurance plan but does not count towards your deductible or co-insurance.5

Detailed explanation of Medicare premiums5

HCPCS (Healthcare Common Procedure Coding System)

A standardized alphanumeric coding system used by medical providers to submit healthcare claims to Medicare and other health insurances.7

HCPCS Level I is comprised of Current Procedural Terminology (CPT), a 5-digit numeric coding system.7

CPT is a uniform coding system used by healthcare providers to describe the medical services they give—like checkups, treatments, or equipment. These labels help make sure insurance companies (like Medicare or private plans) know exactly what was done so they can pay the right amount.7

 

Definitions of HCPCS and CPT from the Centers for Medicare & Medicaid Services7

ICD-10 (International Classification of Diseases, 10th Revision)

ICD-10 stands for the International Classification of Diseases, 10th Revision. It is a system used to code and classify diagnoses and procedures in healthcare.8

In the U.S., it includes:

  • ICD-10-CM: for diagnosis coding in all healthcare settings8
  • ICD-10-PCS: for inpatient procedure coding in hospitals8

 

Definition of ICD-10 from the Centers for Medicare & Medicaid Services8

In-Network Providers

A provider network is a list of healthcare providers who are contracted by an insurance company and provide medical care to those enrolled in plans offered by that insurance company.9

  • The providers in the health insurance plans network are called “network providers.”
  • Every insurance plan provides a list of in-network providers on their patient portals.9

Letter of Medical Necessity (LOMN) and/or Certificate of Medical Necessity (CMN)

A LOMN is a carefully written letter by your physician and/or physical therapist stating why the patient needs a specific piece of equipment, test, treatment, or medication.9

Your medical professional will diagnose your medical condition, include pertinent medical history, outline why that piece of durable medical equipment (DME) is medically necessary for your condition, even if your insurance provider deems certain DME as an accessory and not “medically necessary” under your insurance plan’s policy.10,11

Full Definition of Medical Necessity11

Medicare Part A

Medicare Part A refers to Hospital Insurance.12

It helps cover inpatient hospital care, skilled nursing facility care, hospice services, and some home health care. Most people receive Part A without paying a monthly premium if they or their spouse have sufficient work history (earned through Medicare‑covered employment and accumulated quarters of coverage).

Individuals who are already receiving Social Security or Railroad Retirement Board benefits are automatically enrolled at age 65, while others must apply through the Social Security Administration. Eligibility also extends to people under 65 with certain disabilities or End‑Stage Renal Disease.12

 

Detailed information about Medicare Part A12

Medicare Part B

Medicare Part B refers to Medical Insurance.12

It helps cover services such as doctor visits, outpatient care, preventive services, and medical supplies.

Unlike Part A, Part B requires a monthly premium for all beneficiaries, and individuals may face a late enrollment penalty if they do not sign up when first eligible. People who are already receiving Social Security or Railroad Retirement Board benefits are automatically enrolled, while others must enroll manually during an appropriate enrollment period.12

 

Detailed information about Medicare Part B12

Medicare Advantage Plans (Part C)

Medicare Part C, also called Medicare Advantage, is an alternative way to receive Medicare coverage through private companies approved by Medicare.13

These plans provide all Part A (Hospital Insurance) and Part B (Medical Insurance) benefits and may also offer additional coverage such as vision, hearing, dental, and wellness programs. Most Medicare Advantage plans include prescription drug coverage (Part D).

Medicare pays a fixed monthly amount to the companies offering these plans, and while they must follow Medicare rules, each plan may have different out‑of‑pocket costs and service requirements, including whether referrals are needed or whether members must use in‑network providers.13

 

Detailed information about Medicare Advantage Plans (Part C)13

Medicare Part D

Medicare Part D refers to Medicare drug coverage.14

It helps pay for the brand‑name and generic prescription medications you need. Part D is optional and is offered through private insurance companies approved by Medicare. Even if you are not currently taking prescription drugs, enrolling when you first become eligible is encouraged to avoid a late enrollment penalty if you join a plan later.14

 

Detailed information about Medicare Part D14

Out-of-Network Providers

A provider who is not contracted with your insurance company for reimbursement at a negotiated rate.

If you see an out-ofnetwork provider, or a provider that is not in your insurer’s network, you may be responsible for a higher co-pay, deductible, and out-of-pocket limit. Seeing a provider outside of your network may significantly increase your costs.9

Prior-Authorization

Approval from a health plan that may be required before you get a service or fill a prescription in order for the service or prescription to be covered by your plan.15

 

Full Definition Prior Authorization15

Documents are provided for educational and informational purposes only and do not guarantee coverage or payment. Coverage and payment policies change over time. The accuracy of the information is not guaranteed and should be confirmed with the payor.

 

References

  1. Centers for Medicare & Medicaid Services. Medicare Coverage of Durable Medical Equipment and Other Devices. Available at: https://www.medicare.gov/publications/11045-medicare-coverage-of-dme-and-other-devices.pdf. Accessed January 23, 2025.
  2. Centers for Medicare & Medicaid Services. Durable Medical Equipment Medicare Guidelines for Criteria. Available at: https://www.medicare.gov/coverage/durable-medical-equipment-dme-coverage. Accessed January 23, 2025.
  3. Centers for Medicare & Medicaid Services. Medicare & You 2025. Available at: https://www.medicare.gov/publications/10050-medicare-and-you0.pdf. Accessed January 23, 2025.
  4. Centers for Medicare & Medicaid Services. How to Read an Explanation of Benefits. Available at: https://www.cms.gov/ medical-bill-rights/help/guides/explanation-of-benefits. Accessed January 23, 2025.
  5. Centers for Medicare & Medicaid Services. What Does Medicare Cost? Available at: https://www.medicare.gov/basics/getstarted-with-medicare/medicare-basics/what-does-medicare-cost. Accessed January 23, 2025.
  6. National Council on Aging. What You'll Pay in Out-of-Pocket Medicare Costs in 2025. Available at: https://www.ncoa.org/article/what-you-will-pay-in-out-of-pocket-medicare-costs-in-2025/. Published December 5, 2024. Accessed January 23, 2025.
  7. Centers for Medicare & Medicaid Services. Healthcare Common Procedure Coding System (HCPCS). https://www.cms.gov/medicare/coding-billing/healthcare-common-procedure-system. Accessed September 3, 2025.
  8. Centers for Medicare & Medicaid Services. Introduction to ICD-10. https://www.cms.gov/eHealth/downloads/eHealthU_IntroICD10.pdf. Accessed September 3, 2025.
  9. Centers for Medicare & Medicaid Services. What You Should Know About Provider Networks. Available at: https://www.cms.gov/marketplace/outreach-and-education/what-you-should-know-provider-networks.pdf. Accessed January 23, 2025.
  10. National Association of Insurance Commissioners. Understanding Health Care Bills: What Is Medical Necessity? Available at: https://www.naic.org/documents/consumer_health_insurance_what_is_medical_necessity.pdf. Accessed January 23, 2025.
  11. HealthCare.gov. Medically Necessary - Glossary. Available at: https://www.healthcare.gov/glossary/medically-necessary/. Accessed January 23, 2025.
  12. Centers for Medicare & Medicaid Services. Original Medicare (Part A and B) Eligibility and Enrollment. CMS.gov. Last modified January 8, 2025. https://www.cms.gov/medicare/enrollment-renewal/original-part-a-b. Accessed February 2, 2026.
  13. U.S. Department of Health & Human Services. What is Medicare Part C?. HHS.gov. Published July 22, 2024. https://www.hhs.gov/answers/medicare-and-medicaid/what-is-medicare-part-c/index.html. Accessed February 2, 2026.
  14. Medicare.gov. What’s Medicare Drug Coverage (Part D)?. Centers for Medicare & Medicaid Services. https://www.medicare.gov/health-drug-plans/what-medicare-part-d-drug-coverage-is. Accessed February 2, 2026.
  15. HealthCare.gov. Prior Authorization - Glossary. Available at: https://www.healthcare.gov/glossary/prior-authorization/ Accessed January 23, 2025.
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This glossary includes clear definitions to help you better understand your coverage and the approval process.