Medicare’s Part D income-related monthly adjustment for 2026 adds a second, separate bill on top of whatever a beneficiary’s drug plan already charges, and the five tiers run from $14.50 to $91.00 a month depending on income reported two years earlier. The Centers for Medicare & Medicaid Services set those amounts alongside the rest of the 2026 premium and deductible schedule for a benefit year that began January 1, and the agency says roughly 8 percent of people enrolled in Part D will see one of the five figures added to their bill. The charge does not replace or lower the plan’s own premium; it stacks on top of it.
The Five Tiers Behind the Surcharge
The five-tier structure exists because Congress built Part D’s income-related adjustment on the same income ladder Medicare already uses for Part B, so a beneficiary who pays extra for outpatient coverage typically owes a matching addition for prescription coverage as well. Eligibility for the smallest tier starts once modified adjusted gross income climbs above $109,000 for an individual filer or $218,000 for a married couple filing jointly, measured off the tax return filed two years before the coverage year begins. A retiree who sold a rental property or pulled a large sum from a retirement account in 2024 can cross that line for 2026 even if income drops back down before the bill arrives, because the calculation only looks at the return the IRS already has on file.
That $109,000-and-$218,000 entry point carries the smallest of the five monthly add-ons, $14.50, and the amount climbs in four further steps to $37.50, then $60.40, then $83.30, and finally $91.00 for the highest earners, according to the fact sheet the Centers for Medicare & Medicaid Services published alongside the 2026 premium and deductible schedule. Each step corresponds to a wider income bracket above the entry line, so two beneficiaries enrolled in the exact same drug plan can end up owing very different total monthly bills purely because of what their tax returns showed two years earlier.
Medicare does not average the tiers or phase a household gradually from one step to the next; crossing into a bracket, even by a small margin, means owing that bracket’s full monthly amount for every month of the coverage year, not a prorated fraction of it. A married couple whose joint income lands one dollar above a bracket line owes the same surcharge as a couple whose income sits near the top of that bracket, which is why the jump between tiers can feel abrupt to a household that crossed a threshold without realizing how the schedule was built.
CMS frames the adjustment as reaching a minority of the program rather than the typical enrollee: the agency puts the share of Part D beneficiaries who owe one of the five amounts at roughly 8 percent. That leaves the large majority of the program paying only their plan’s own premium, but for the minority who do cross the income line, the surcharge is not optional, is not waived for a low-cost plan, and does not shrink because a beneficiary switched to a cheaper drug formulary partway through the year.
Inside the kit: 51 state Medicare cost-help packs, the new Part D out-of-pocket cap, the prior-authorization appeal steps and a medication and cost tracker. Open The Medicare Cost & Coverage Protection Kit.
Billed Apart From Whatever the Plan Already Costs
The surcharge is not folded into the premium a beneficiary agreed to when they enrolled in a specific Part D plan; it is a separate government charge layered on top of it, calculated the same way regardless of which insurer sold the underlying coverage. CMS’s own description of the amount treats it as an addition charged in addition to the plan premium, not a replacement component of it, which is why two people enrolled in the identical low-cost plan can end up with very different total monthly bills once one of them crosses the income threshold and the other does not.
For most affected beneficiaries, the amount is withheld directly from a Social Security payment rather than added to whatever statement the private drug plan sends, which means the surcharge can be easy to overlook against a premium bill that never mentions it. Someone who is not yet collecting Social Security, or whose benefit is too small to cover the full amount, is billed by Medicare directly instead, on a separate schedule from the private plan’s own billing cycle. Either way, comparing plan premiums during open enrollment tells a beneficiary nothing about this second charge, because the amount is fixed by income rather than by which plan they pick.
The Two-Year Lookback That Sets the Bill Before the Year Starts
The income figure behind each 2026 surcharge was locked in long before the coverage year began, because Social Security determines the adjustment from the federal tax return filed two years earlier rather than from current earnings. Modified adjusted gross income, for this purpose, is the adjusted gross income reported on that return plus any tax-exempt interest, and the IRS is the source Social Security draws it from rather than a fresh income check closer to the coverage year. That structure means a 2026 surcharge reflects a household’s 2024 finances, whatever they look like now.
The lag can catch people off guard in both directions. A worker who sold a business or took a one-time retirement-account distribution in 2024 can be paying the higher 2026 surcharge on income they no longer have, while someone whose income only rose above the threshold in 2025 will not see a matching charge until a later coverage year, once that return works its way through the same two-year pipeline. Because the determination rides entirely on a return the IRS already processed, there is no in-year adjustment tied to a beneficiary’s actual 2026 income, only the figure Social Security pulled from the return on file.
CMS published the full 2026 schedule, covering the Part B premium, the Part B deductible, and both sets of income-related adjustments for Part B and Part D, in the same November 2025 fact sheet that sets the five Part D amounts at $14.50, $37.50, $60.40, $83.30 and $91.00. That document remains the government’s own record of what the 2026 surcharge is, who it reaches, and how it is billed, and it says nothing about any figure beyond the 2026 benefit year.
The Surcharge That Arrives Separately
Nothing about the surcharge arrives on the same statement as the rest of a household’s Medicare costs; it shows up apart from the drug plan’s own premium, on its own schedule, often withheld quietly from a Social Security payment. The gap this leaves is rarely the dollar figure itself; it is the absence of a single place that lines the surcharge up against the deductible, the premium, and the plan’s own coverage rules so a household can see the full picture at once.
The Medicare Cost & Coverage Protection Kit is a 10-page kit that lines up the new Part D out-of-pocket cap next to a medication and cost tracker, so a household can see where an income-related charge like this one sits against everything else Medicare already bills for.
Look up the prior-authorization appeal steps inside The Medicare Cost & Coverage Protection Kit.
This article was researched and drafted with the assistance of AI and reviewed by The Money Overview editorial team.
