NO. You cannot collect any money from the patient, whether you are a Medicaid provider or not. This patient is called QMB - Qualified Medicare Beneficiary (dual eligible), and even if NO ONE pays you, you cannot collect from the patient. One instance of this would be if the patient has not yet met their deductible with Medicare.
It is a huge problem nationwide of physicians collecting money from QMB patients.
Here is an article (click me).
Here is a relevant excerpt:
Providers who bill QMBs for amounts above the Medicare and Medicaid payments (even when Medicaid pays nothing) are subject to sanctions. Providers may not accept QMB patients as "private pay" in order to bill the patient directly, and providers must accept Medicare assignment for all Medicaid patients, including QMBs.
Info straight from Medicare: If you’re eligible, the QMB Program helps pay for Part A and/or Part B premiums. Medicare providers aren’t allowed to bill you for services and items Medicare covers, including deductibles, coinsurance, and copayments, except outpatient prescription drugs. Pharmacists may charge you up to a limited amount (no more than $4.00 in 2021) for prescription drugs covered by Medicare Part D. If you get a bill for these charges, tell your provider or the debt collector that you’re in the QMB Program and can’t be charged for Medicare deductibles, coinsurance, and copayments. If you’ve already made payments on a bill for services and items Medicare covers, you have the right to a refund. If you’re enrolled in a Medicare Advantage Plan, you should also contact the plan to ask them to stop the charges.