42 CFR §489.22

1. (a)A provider may not require an individual entitled to hospital insurance benefits to prepay in part or in whole for inpatient services as a condition of admittance as an inpatient, except where it is clear upon admission that payment under Medicare, Part A cannot be made.
2. (b)A provider may not deny covered inpatient services to an individual entitled to have payment made for those services on the ground of inability or failure to pay a requested amount at or before admission.
3. (c)A provider may not evict, or threaten to evict, an individual for inability to pay a deductible or a coinsurance amount required under Medicare.
4. (d)A provider may not charge an individual for (1) its agreement to admit or readmit the individual on some specified future date for covered inpatient services; or (2) for failure to remain an inpatient for any agreed-upon length of time or for failure to give advance notice of departure from the provider's facilities.