Short answer: No. Medicare providers may not bill someone in QMB for Medicare deductibles, coinsurance or copays on Medicare-covered services, even when the state pays the provider less than the full cost-sharing.
Medicare.gov: if a person is in QMB, Medicare providers aren’t allowed to bill them for services and items Medicare covers, including deductibles, coinsurance and copayments. The person may still get a bill for a small Medicaid copayment if one applies.
The protection holds even when the state pays little or nothing. Federal law (42 U.S.C. 1396a(n)) lets a state cap its payment of Medicare cost-sharing at the Medicaid rate, but when it does, Medicare’s payment plus the state’s payment counts as payment in full, the person has no legal liability for the rest, and providers that charge anyway face sanctions.
The bar covers Medicare cost-sharing. Services Medicare doesn’t cover are a separate question. Tell QMB people to show both their Medicare card and their Medicaid or QMB card every visit.