The payments, expected to arrive in early October, will come from the $2 billion Medicare Improvement Fund and are intended to help eligible beneficiaries offset the cost of their Medicare Part B premiums, according to the White House.
Most eligible seniors will receive the money through direct deposit, while those without direct deposit will receive checks at the mailing addresses registered with Medicare.
The White House said most Medicare Part B enrollees qualify, while people whose premiums are already paid through Medicaid and those who pay an Income-Related Monthly Adjustment Amount will not receive the payment.
The announcement came as Trump returned to Washington from a midterm campaign rally in Mobile, Alabama, with the elections barely a month away and Republicans holding narrow majorities in both chambers of Congress.
The timing has put the payment under heightened scrutiny, particularly because it follows a string of other financial promises from Trump that are explicitly tied to the Republican Party's electoral fortunes.
Last month, Trump promised a $5,000 “dividend” to every adult American if Republicans retain control of Congress, presenting the proposal as a reward made possible by his economic policies.
That proposal has already encountered substantial criticism over its cost and financing.
CBS News reported that a nationwide $5,000 payment would cost more than $1.2 trillion and would require congressional action, while tariff revenue cited as a potential funding source has fallen far short of the amount needed.
FactCheck.org similarly found that Trump's proposed dividend would require more than six years of tariff revenue to cover its estimated $1.2 trillion price tag.
Some Republicans have also expressed concern about the proposal's fiscal consequences, including its potential effect on inflation and the federal balance sheet.
Against that backdrop, Trump's new Medicare payment has inevitably become part of a larger debate over the president's growing reliance on direct financial promises as the midterms draw closer.
Reuters reported that the Medicare payment is the latest in a series of financial measures introduced ahead of the elections, including separate $500 payments to nearly 1 million Americans enrolled in Affordable Care Act plans.
Critics of the administration's approach have questioned whether such measures represent durable economic policy or short-term financial relief promoted at a politically advantageous moment.
The Washington Post reported that Trump's broader efforts to ease consumer pressures have encountered resistance from farmers, oil companies, lawmakers and economists, while the proposed $5,000 payments have prompted concerns about inflation and the national debt.
The controversy has also extended to government-funded messaging featuring Trump.
Reuters reported that Democratic lawmakers have requested investigations into television advertisements featuring Trump that were financed with $20 million in taxpayer money through the Department of Homeland Security, arguing that the advertisements could constitute political messaging disguised as government communication.
The issue has generated criticism from some Republicans as well, with concerns raised over whether taxpayer funds should be used for material that promotes the president.
Meanwhile, Trump's Medicare announcement offers beneficiaries only a one-time payment rather than a permanent reduction in their Medicare costs.
For millions of older Americans facing recurring healthcare expenses, the $90 payment may provide immediate relief, but it does not alter the underlying cost of Medicare Part B premiums.
The announcement therefore arrives as both a concrete benefit for eligible seniors and another episode in an increasingly contentious election-year debate over Trump's economic promises, federal spending and the use of government resources.
With the midterm elections approaching, the administration is portraying the payment as healthcare relief, while critics are focusing on its timing alongside a succession of other financial promises tied to Trump's political agenda.
The immediate beneficiaries will receive $90 in October.
The broader political dispute, however, is likely to continue well beyond the arrival of the checks.