How long does it take to get Medicare/Medicaid benefits re-instated for an elderly Alzheimer's patient who must return to the U.S. for assisted care (Washington state) after living outside the U.S. for eight years?
The Medicare Consumer Guide details the steps to take. As noted by @mkennedy, there may be additional requirements, and establishing competency and guardianship can be lengthy. Once any prerequisites and eligibility are met, the Social Security Administration process is quite immediate, taking 3-4 weeks. Should there be delays, benefits, if granted, are usually retroactive.
Medicare Eligibility If You Live Overseas or Are Moving Back to the U.S.
Typically, U.S. citizens and legal permanent residents of at least five continuous years are eligible for Medicare when they turn 65 or at any age through disability.
Are you a returning U.S. citizen?
If you didn’t sign up for Medicare because you were out of the country, you may be able to enroll in Part A and Part B after you return to the country and establish residency. [Y]ou must be either a U.S. citizen or permanent legal resident of at least five continuous years to be eligible.
Generally, if you return to the U.S. after living abroad, you can sign up for Medicare Part A and/or Part B during the General Enrollment Period (January 1 through March 31). You might have to pay a late-enrollment penalty. But, in some cases, you might qualify for a Special Enrollment Period.
Enrolling in Medicare after you return to the U.S.
Once you return to the U.S. and establish residency in the country, you may be eligible for Medicare Part A and/or Part B if you meet the above-mentioned citizenship and legal permanent residency requirements. You can sign up through the Social Security Administration:
Online: Visit http://www.ssa.gov/
By phone: Call 1-800-772-1213 (TTY users call 1-800-325-0778), Monday through Friday, from 7AM to 7PM.
In person: Visit your local Social Security office.