The hospital told me that Medicare will no longer pay for my hospital stay. If I stay in the hospital, will I be personally responsible for the hospital bill?

Yes, you will be responsible for the bill unless a Medicare Peer Review Organization (PRO), an Administrative Law Judge (ALJ), or a U.S. District Judge finds that Medicare should continue to cover your hospital expenses. You must receive written notice that Medicare will no longer cover your hospital stay. If you receive such a notice, first look and see whether the notice is from the hospital or the Medicare PRO. The PRO makes the decision for Medicare whether the care you are receiving is necessary and reasonable. PROs are run by physicians and are not connected to the hospital in which you are staying. 

If the hospital decides that you no longer qualify for Medicare coverage, it must give you three days of advanced notice to leave the hospital before the coverage stops. This is the first notice you would receive. 

The hospital must notify the PRO. The PRO will then check with your treating physician and decide whether your Medicare coverage should continue. Even if your physician feels you should stay, the PRO can disagree. If the PRO decides that your coverage should end, then the PRO must tell you the day after it is notified by the hospital that your coverage will stop. This is the second notice you would receive. 

You can ask the PRO for a reconsideration of its decision. You should request the reconsideration in writing. You can send this letter to the PRO or the Social Security Administration. However, you may request an expedited reconsideration; this request you must make directly of the PRO. You can call the PRO, but sending a written request is best. The request must be made within three days of the notice of termination of your coverage. If you choose to make a normal request for reconsideration instead of an expedited request, you must file within 60 days after receipt of the initial notice. The PRO then must reconsider either type of request within three days. 

If you receive another unfavorable decision by the PRO, you can file an appeal with an ALJ and then you can go to the Medicare Appeals Council. There is no money requirement for the Appeals Council but you must file with in 60 days of the ALJ decision. After this, you may also then file with a U.S. District Judge. To appeal to an ALJ, the amount you owe must be at least $150. To appeal to the District Judge, the amount you owe must be at least $1,460. 

It is important for you to decide whether or not you are going to stay in the hospital and fight the decision, or make arrangements to leave. If you stay in the hospital and then lose all your appeals, you will have to pay for the non-covered time you stayed in the hospital. Of course, if you win, Medicare will cover the entire stay. If your physician agrees that you are well enough to leave the hospital, your chances at appeal are not very good. If your physician thinks you should stay, then you have a difficult decision to make: whether to stay in the hospital to receive the care that your doctor thinks you need and possibly incur large medical bills, or whether to leave the hospital and try to get treatment with your doctor in another setting. (See also the question Bills Beyond Medicare Limits, p. 34.)  

For more information, see: 42 U.S.C. §§ 1320c-3, 1395f(a)(2), 1395y(a)(1), 1395q(d) (2015); 42 C.F.R. §§ 412.42(c)(3), 476.70, 476.78(b)(3)-(4), 476.85, 476.90, 476.94, 478.16, 478.18, 478.20, 478.32, 478.40, 478.46 (2015); Joan M. Krauskopf et al., Elderlaw: Advocacy for the Aging §§ 10.101-.106 (2nd ed. 1993).