How Medicare Pays: Parts A, B and D and the Part C Boundary

How Medicare pays providers and plans depends on the payment route: Original Medicare pays providers and suppliers for covered care, while Medicare Advantage and Part D pay private organizations to provide benefits. A hospital discharge, a physician service and a drug plan’s rebate report affect payment in different ways.

If you work in billing, clinical care, finance or plan operations, you may know where the account sent to Medicare parts company with the work. Medicare fraud exploits that gap at taxpayers’ expense. We connect what the business did, what it told Medicare and the money it received.

What Parts A, B and D Mean for Payment

Payment differences across Medicare Parts A, B and D begin with the benefit and the recipient. Part A covers inpatient hospital care, skilled nursing facility care, hospice and certain home health services. Part B covers physician services, outpatient hospital care, diagnostic testing, durable medical equipment, qualifying ambulance transport and other specified benefits. Part D provides outpatient prescription coverage through approved sponsors.

The Medicare Trustees’ 2026 report places Part A in the Hospital Insurance trust fund. Parts B and D have separate accounts within Supplementary Medical Insurance. Part C, Medicare Advantage, delivers Medicare benefits through private plans using A/B financing. A plan offering drug coverage also has a distinct Part D payment component.

The drug boundary deserves particular care. Part B covers specified drugs, including some administered by clinicians and some taken orally. The Medicare drug-benefit manual ties the boundary to the drug and the circumstances in which the patient receives it. An injection is not automatically Part B, and an oral drug is not automatically Part D. The Trustees’ 2026 report describes payment for most physician-administered drugs as average sales price plus 6 percent. The drug’s payment method matters alongside the service that delivered it.

How Original Medicare Pays Providers

Original Medicare pays providers through a Medicare Administrative Contractor. The provider’s enrollment and billing authority come first, followed by the service, supporting records, claim, contractor processing, remittance and payment. Corrections and recoveries can follow the payment.

These contractors are private organizations administering Original Medicare. The Centers for Medicare & Medicaid Services describes their work as processing claims, making payments, enrolling providers, reviewing selected medical records and auditing institutional cost reports. A contractor paying a physician’s claim performs a different job from a Medicare Advantage insurer receiving money to cover an enrollee.

The remittance advice, commonly an 835, explains the contractor’s decision and adjustments. The electronic funds transfer shows the money transferred. Provider-level offsets can change the deposit even when the current claims show particular payment amounts. Those differences matter when we connect the service records, claims and payment trail with an insider’s account of what happened.

How Medicare Part B Pays Professional Services

Part B pays many professional services through the Physician Fee Schedule. The service code leads to relative value units for the clinician’s work, practice expense and malpractice expense. Geographic adjustments apply to those components, and a conversion factor turns the result into a payment amount.

The Physician Fee Schedule covers physicians and other eligible health care professionals, as well as services such as radiology and certain diagnostic tests. The code, place of service, locality, practitioner status and applicable adjustments all matter. A conversion factor by itself cannot explain what a particular claim should have paid.

Setting changes whose resources Medicare is paying for. In an office, the professional payment can include the practice’s overhead. In a hospital setting, the facility supplies resources that can appear on its own claim, while the clinician bills for professional work. We look at whose resources the claim says were used, and what the encounter records show.

Assignment means accepting the Medicare-approved amount as full payment. Medicare’s cost guidance describes the usual Part B beneficiary coinsurance as 20% after the deductible when the provider accepts assignment.

How Medicare Pays Hospitals and Facilities

Medicare pays institutions through systems built around the setting and the unit of care. Under the acute inpatient prospective payment system, a hospital generally receives payment per discharge. The case falls into a diagnosis-related group, whose weight reflects the resources normally used for that group of patients. Geographic and hospital-specific adjustments affect the payment, and unusually costly cases can qualify for additional outlier payments.

Disproportionate share hospital payments increase reimbursement for qualifying hospitals serving low-income patients. Approved teaching hospitals receive an indirect medical education adjustment. Those additions depend on facts about the hospital, as well as the patient classification.

The hospital’s itemized charges therefore tell a different story from the payment calculation. The classification of the stay matters. So do the facts supporting any additional payment. This is where someone who knows the patient’s care can explain why a billing description matters to the money.

Hospital outpatient care runs through a separate Part B prospective payment system. Skilled nursing facility payment uses covered days and a case-mix-adjusted daily amount. Hospice has daily payment rates and annual caps. The payment unit changes even when the same patient moves between these settings.

Home health makes the distinction especially clear. Since January 2020, the home health payment system has used a 30-day payment period, with case-mix and wage adjustments. Periods below the applicable visit threshold receive per-visit payment. Eligibility recertification remains on a 60-day cycle, with plan-of-care review on that cycle or sooner when the patient’s condition requires it. The payment period and the clinical certification period are different clocks.

Part A’s hospital and skilled nursing benefit periods also differ from the calendar year. Admission status matters: observation ordinarily remains outpatient, and an overnight stay alone does not establish inpatient admission. A transfer from a hospital to a skilled nursing facility does not simply start a new benefit period.

Prospective payment also leaves room for separate cost-based components and later adjustments. Interim payments, the certified cost report, audit adjustments and final settlement each tell part of the financial story. An administrator or chief financial officer signs the cost-report certification. The payment received during the year and the amount settled after review depend on different representations.

How Medicare Part D Pays Sponsors

Part D pays a sponsor in advance and later reconciles several payment streams. The pharmacy transaction feeds that process, but it is only one part of the federal payment calculation.

The sponsor’s bid estimates the revenue needed to provide coverage. The direct subsidy reflects the approved bid, enrollee risk and the applicable premium component. Federal reinsurance and low-income cost-sharing support add other payments. The sponsor may delegate work to a pharmacy benefit manager, but it retains responsibility for its contract with the Centers for Medicare & Medicaid Services.

Prescription drug event records describe covered costs and the amounts assigned to different payers. A sponsor’s accepted events, corrections and deletions help establish what entered the federal calculation. Rebate and other price-concession reporting then affects the net drug cost. Direct and indirect remuneration, usually called DIR, reaches beyond payments labeled rebates.

The Centers for Medicare & Medicaid Services reconciles prospective payments against the applicable subsidies and risk-corridor amounts. Risk corridors compare adjusted allowable costs with a target based on the bid, sharing specified gains or losses between the sponsor and the government. The resulting settlement can change later monthly payments or produce a lump-sum adjustment.

The coverage year matters here. The Centers for Medicare & Medicaid Services’ 2025 Part D redesign instructions changed payment responsibility as the coverage gap ended and the Manufacturer Discount Program began. Its 2026 instructions address selected drugs with negotiated prices and their subsidy treatment. A rebate report and reconciliation have to be read against the rules for their year.

Medicare Payment Versus Medicare Advantage Capitation

The difference between Medicare payment and Medicare Advantage capitation is who receives the federal money and what it covers. Original Medicare pays against a service, stay or other defined unit. Medicare Advantage receives an advance monthly payment for an enrollee, adjusted through its payment system. The plan then pays providers under its own arrangements.

Bids, county benchmarks and risk adjustment affect the federal payment to the plan. Applicable quality bonuses increase benchmarks. When a bid falls below its benchmark, a share of the difference funds extra benefits or reduces enrollee costs. That rebate share depends on the plan’s quality rating.

The plan’s payment to a hospital or physician is a separate transaction. When drug coverage sits inside a Medicare Advantage plan, its Part D component retains its own payment and reporting rules.

Part C spending already draws on the A/B accounts. Adding it again to those account totals counts the same benefit money twice. Enrollment requires the same care: a person can appear in A, B and D figures while receiving benefits through a private plan. The labels describe overlapping coverage, not separate people.

When Another Payer Pays First

Other coverage can make Medicare the secondary payer. Employment coverage and insurance responsible for an injury can change the payment order. Medicare can make a conditional payment when the primary payer has not paid promptly, then seek repayment.

For someone covered by both programs, Medicare ordinarily pays first for Medicare-covered services, while Medicaid remains the payer of last resort. Medicare and Medicaid have different payment responsibilities, even when both appear in one patient’s billing history.

A crossover sends claim information to another payer. It establishes the transfer of information, while that payer’s response and payment records establish what happened next. For a Qualified Medicare Beneficiary, the provider cannot collect covered A/B cost sharing from the patient even when Medicaid pays nothing. The Centers for Medicare & Medicaid Services guidance on these billing protections puts that distinction directly into the provider’s accounts receivable.

Where a False Account of the Work Changes Payment

A false Medicare payment representation can concern the service, the classification, the institution’s costs or the drug plan’s net spending. Knowing the payment unit tells us which business record connects the conduct to the money.

The Congressional Research Service’s 2011 report, Medicare Program Integrity: Activities to Protect Medicare from Payment Errors, Fraud, and Abuse, explained why different payment structures create different incentives. Payment for specified services can reward overstated services or unnecessary care. Advance plan payments create different pressures around enrollment, bids and the care delivered.

The report also identified the tension between paying promptly and verifying the underlying account:

We see the absurdity in that sequence: pay first, then chase money that should never have gone out. The delivery record or internal warning can explain what a paid claim concealed. An insider knows the work behind the transaction.

Walgreens’s agreement concerning uncollected prescriptions set a $97,814,790 settlement, including prior refunds. In that agreement, the government alleged that Walgreens processed prescriptions that patients never picked up or received and retained payments despite non-delivery. The connection runs from dispensing and delivery to the paid claim and the money kept.

Silver Lake Hospital agreed to pay $18,636,282 to resolve allegations involving excessive outlier payments and retained reconciliation debts. The settlement agreement described allegations that charges rose without corresponding costs, followed by knowing or reckless avoidance of reconciliation debts. Both the original payment and the later reconciliation mattered.

Elixir agreed to a $101 million payment obligation to resolve allegations of false rebate reporting. The government alleged in the settlement agreement that retained manufacturer rebates were reported as service fees on Elixir Insurance Company’s DIR reports. The whistleblower’s complaint alleged that the explanation itself was manufactured:

Rebates, renamed. We see more than an accounting label in those allegations: money that should have reduced Medicare’s drug costs was presented as payment for services. The complaint alleged that documents were fabricated to make that description stick.

A whistleblower case under the False Claims Act can pay 15% to 30% of what the government recovers.

When You Know What the Payment Record Leaves Out

If you know why a claim, cost report or drug-plan submission tells a different story from the work, speak with our whistleblower experts about the Medicare payment behind it. We work beside you to connect that knowledge to the decisions and money that can build your strongest Medicare whistleblower case. We stay with you through the whole journey and bring in Medicare fraud whistleblower lawyers who know the payment system involved.