What is Medicare billing?

Medicare billing is the process of submitting claims to the Medicare program for covered services provided to Medicare beneficiaries. Part A covers inpatient and facility services billed on the UB-04. Part B covers physician and outpatient services billed on the CMS-1500 under the physician’s NPI. Part C routes claims to private Medicare Advantage plans that require separate credentialing. With over 54% of Medicare patients in Advantage plans, most Medicare claims today go to private plans rather than to traditional Medicare directly.

What is the difference between Medicare Part A and Part B billing?

Part A covers inpatient and facility services and is billed by hospitals and skilled nursing facilities on the UB-04 form under the facility NPI. Part B covers physician professional services and outpatient care, billed on the CMS-1500 under the physician’s individual NPI. A physician treating a hospitalized patient bills Part B for their professional fee while the hospital separately bills Part A for facility costs. Both claims go to Medicare but follow completely different billing pathways, forms, and fee schedules.

How does Medicare Advantage billing differ from traditional Medicare?

Medicare Advantage claims go to the private plan administering the patient’s coverage, not to Medicare directly. Each plan has its own network, fee schedule, and prior authorization requirements. A provider enrolled with traditional Medicare is not automatically in-network with any Advantage plan. Separate credentialing is required with each plan, taking 90 to 120 days. With over 54% of Medicare patients in Advantage plans, managing Advantage credentialing is now as important as managing traditional Medicare enrollment.

What does Medicare billing require before providers can bill?

Before billing Medicare, a provider must have an active PECOS enrollment with their NPI linked to an approved Medicare enrollment record. PECOS enrollment takes 60 to 90 days. Claims submitted under a non-enrolled provider deny automatically with no retroactive payment at most payers. Starting PECOS enrollment the day a new provider hire is confirmed is the only way to minimize the billing gap between their first patient encounter and their first collectible Medicare claim.

What is the Medicare timely filing deadline?

Medicare requires claims within 12 months of the date of service. This is one of the most generous timely filing windows in healthcare billing. However, it is not unlimited. Claims submitted after 12 months deny and cannot be appealed based on late filing. Charge lag, pending claim holds, and billing backlogs can all push claims past even this extended window. Proactive charge entry standards and weekly pending claim reviews prevent timely filing from becoming a write-off category.

What is a Medicare ABN and when is it required?

An Advance Beneficiary Notice is a required written notice given to a Medicare patient before a service Medicare is likely to deny, allowing the provider to collect from the patient if Medicare doesn’t pay. Without a valid ABN, the provider cannot collect from the patient on a non-covered service and absorbs the full cost. The ABN must be given before the service, use the current CMS-approved form, and identify the specific service and the reason Medicare may not cover it.

What is Medicare revalidation and what happens if it is missed?

Medicare revalidation is the five-year renewal of a provider’s PECOS enrollment. Missing the deadline results in deactivation of Medicare billing privileges, causing all Medicare claims to deny until revalidation is completed. CMS sends notices to the address and email in PECOS. Outdated contact information means the notice is never received. Checking PECOS annually for every enrolled provider to confirm contact information is current and reviewing the revalidation due date is the only reliable prevention.

How Medicare Billing Works in 2026

How Medicare Billing Works in 2026 | Qualigenix