Millions of Americans on Original Medicare face a cost-sharing split that leaves them responsible for 20 percent of every approved doctor bill, with no annual ceiling on what they might owe. As the Part B deductible rises to $283 in 2026, that open-ended exposure puts growing pressure on beneficiaries who rely on specialists or ongoing outpatient care, and it sharpens the case for Medigap policies designed to absorb the gap.
Why the 20 percent coinsurance hits harder in 2026
Original Medicare’s cost-sharing formula is straightforward but unforgiving. After the yearly Part B deductible is met, beneficiaries typically owe 20 percent coinsurance on the Medicare-approved amount for covered physician services, outpatient procedures, and durable medical equipment. Medicare picks up the other 80 percent. The problem is what happens when those 20 percent charges stack up across multiple visits, imaging studies, or lab panels in a single year.
Unlike most employer-sponsored health plans or Medicare Advantage contracts, Original Medicare does not include a spending cap on a beneficiary’s yearly out-of-pocket costs for Part A and Part B services. A retiree who needs frequent specialist consultations, chemotherapy infusions, or physical therapy sessions can watch bills accumulate without any built-in safety net. The 2026 Part B deductible of $283, set under the Social Security Act, adds another fixed cost before the 80/20 split even begins.
That combination creates a specific financial risk for people on fixed incomes. A beneficiary seeing two or three specialists regularly could face thousands of dollars in annual coinsurance alone, and nothing in the Original Medicare structure caps that total. The gap between what Medicare pays and what a patient owes is precisely what Medigap policies exist to fill, especially for those who plan to remain in Original Medicare rather than switch to a private Medicare Advantage arrangement.
How Medigap plans close the 80/20 gap
Medigap policies, sold by private insurers, are standardized supplements that pay some or all of the cost-sharing Original Medicare leaves behind. When a beneficiary with both Original Medicare and a Medigap plan receives a covered service, Medicare pays first and the Medigap plan typically pays second, based on the benefits outlined in the policy. The practical effect is that the 20 percent coinsurance a patient would otherwise owe can be reduced or eliminated, depending on which lettered plan the person holds.
Among the ten standardized plan types, Plans K and L stand out because they introduce what Original Medicare itself lacks: an annual out-of-pocket limit. These plans cover a percentage of Part A and Part B coinsurance and copayments during the year, then, once a beneficiary hits the plan’s yearly maximum and has paid the Part B deductible, they pay the full share of covered costs for the rest of the calendar year. That structure converts an open-ended liability into a bounded one, which is a meaningful distinction for anyone anticipating heavy utilization.
Other Medigap options, such as Plans G and N, do not have an explicit out-of-pocket maximum but are designed to cover most or all Part B coinsurance for approved services after the deductible. For beneficiaries who can afford higher monthly premiums, these plans effectively smooth expenses across the year, trading unpredictable bills for a predictable payment. In all cases, Medigap coverage is paired with Original Medicare and cannot be combined with Medicare Advantage.
Who is most exposed to uncapped costs
The people most vulnerable to the 20 percent coinsurance are those with chronic or complex conditions that require frequent outpatient care. Cancer patients undergoing infusion therapy, individuals with advanced heart or lung disease, and those recovering from major orthopedic surgery may cycle through multiple specialists, tests, and therapies in a single year. Each encounter generates a new Part B charge, and therefore a new coinsurance bill, until and unless a Medigap plan or other supplemental coverage intervenes.
Geography and local practice patterns can compound the risk. In regions where specialists are in short supply, patients may need to travel farther and rely more heavily on hospital-based outpatient departments, where approved charges are often higher than in independent clinics. Even though Medicare standardizes its share of the payment, 20 percent of a larger approved amount still lands on the beneficiary.
The hypothesis that rising deductibles and high specialist use in certain states will drive more beneficiaries toward Plans K and L is plausible but not yet confirmed by public enrollment data. CMS has not released state-level breakdowns linking specialist utilization rates to year-over-year shifts in Medigap plan selection. Without that data, the connection remains an informed inference rather than a documented trend.
Medigap versus Medicare Advantage
For some enrollees, Medicare Advantage offers another way to manage risk. These private plans must include an annual maximum on in-network out-of-pocket costs for Part A and Part B services, a feature that Original Medicare lacks. However, they typically use provider networks and prior authorization rules, which can limit flexibility compared with the nationwide access that comes with Original Medicare plus Medigap.
Beneficiaries choosing between these paths are weighing different kinds of protection. Medigap aims to neutralize the 20 percent exposure while preserving broad provider choice. Medicare Advantage aims to cap total spending within a managed-care framework. As Medicare describes in its overview of coverage choices, people generally must decide whether to stay in Original Medicare with optional Medigap or enroll in a Medicare Advantage plan, since the two approaches are not designed to be layered together.
In 2026, as the Part B deductible ticks higher and health care prices continue to climb, the absence of an out-of-pocket ceiling in Original Medicare will matter more for anyone who expects regular outpatient care. For those beneficiaries, understanding how Medigap reshapes the 80/20 split-and how it compares with Medicare Advantage-will be central to keeping necessary treatment financially sustainable.
