How to bill Medicare Part B professional claims

Part B professional claims cover services furnished by physicians and eligible non-physician practitioners in settings such as offices, outpatient departments, and via telehealth. Before any claim can be paid, the rendering and billing entities must hold active Medicare billing privileges. Enrollment is completed through PECOS, the CMS Medicare enrollment system, using the applicable CMS-855 application for the individual or organization. Whether a provider is enrolled as participating or non-participating affects how assignment and beneficiary cost-sharing are handled, so that status should be settled before services are billed.

Coverage confirmation happens at the front end. Verifying active Part B eligibility, the correct Medicare Beneficiary Identifier, and any other coverage that pays before Medicare prevents a large share of downstream denials. When another payer is primary under Medicare Secondary Payer rules, that order must be identified up front because it changes how — and when — Medicare is billed.

Not every service is covered, and coverage can be conditioned on documented medical necessity through national or local coverage determinations. Providers confirm current coverage policy with the servicing contractor rather than assuming a service is payable. When a normally covered item may be denied as not reasonable and necessary, an Advance Beneficiary Notice may be appropriate before the service is furnished.

Professional (Part B) services are reported on the professional claim format — the CMS-1500 for paper and its electronic equivalent — as distinct from the institutional UB-04 used for facility billing. A clean claim carries complete and internally consistent data: correct provider identifiers (NPI), the beneficiary's MBI, accurate place-of-service coding, and diagnosis-to-service linkage that supports medical necessity. Diagnoses are reported from the ICD-10 code set and services from the CPT/HCPCS code sets, each maintained by its respective steward; billers should describe and apply these concepts rather than rely on memorized descriptors.

Modifiers, units, and dates must reflect what was actually documented. Some Part B scenarios — such as incident-to or split/shared services, drugs and biologicals billed under Part B, and telehealth — carry specific coding and supervision conditions that CMS defines and periodically updates. Because these requirements change, the current MLN guidance and Internet-Only Manuals are the authoritative reference rather than any single fixed rule.

The billing entity assigns charges consistently with its fee schedule and its assignment decision. Medicare pays covered professional services based on its physician fee schedule; the specific allowed amounts and payment rules are set by CMS and vary by locality and year, so current schedules should be consulted rather than quoted from memory.

Medicare Part B claims are processed by Medicare Administrative Contractors, each responsible for a defined jurisdiction. Routing a claim to the correct MAC for the place where the service was furnished is essential; a misrouted claim will not adjudicate correctly. Most claims are submitted electronically, typically through a clearinghouse or an approved electronic pathway, which supports faster acknowledgment and error reporting than paper.

Medicare enforces a timely filing requirement measured from the date of service. The specific period and its narrow exceptions are set by CMS; because the boundaries and any exceptions are defined in federal rules, the current CMS source should be checked rather than an assumed deadline. Claims filed after the window are generally denied for untimely filing.

After submission, the claim moves through adjudication. Electronic acknowledgments confirm receipt or report front-end rejections that must be corrected and resubmitted. Distinguishing a rejection (never accepted, resubmit corrected) from a denial (adjudicated and payment refused, which may require appeal) determines the right next step.

Medicare returns an electronic remittance advice (ERA) explaining how each service was adjudicated — paid, adjusted, or denied — using standardized claim adjustment and remark codes. Posting reconciles the remittance against expected allowed amounts and moves any patient responsibility (deductible, coinsurance) to the correct next step, including secondary billing where coordination of benefits applies. The beneficiary receives a parallel Medicare Summary Notice describing the same activity.

Denials and underpayments are worked, not written off by default. Reading the adjustment and remark codes identifies the cause — for example, missing information, a coverage determination, or an eligibility issue — and points to the correction or the appeal path. Medicare provides a multi-level appeals process for denied claims, with its own deadlines defined by CMS.

When Medicare pays after another primary payer, or identifies an overpayment, additional handling applies. Overpayments are subject to return and potential recoupment under CMS rules and program integrity guidance. Tracking these exceptions systematically protects both compliance and the revenue cycle, and the applicable timeframes should be confirmed against the current CMS manuals rather than assumed.