Not by law, but your private insurance may insist that you do so.
Get them from the source http://www.medicare.gov/
The Medicare Modernization Act of 2003 (MMA) provided for a special enrollment period for Medicare Part B for TRICARE beneficiaries who have Medicare Part A. If you have Medicare Part A (which generally pays for hospital care) and don't have Medicare Part B (which generally pays for doctor visits) you may be able to enroll in Part B without paying a late enrollment penalty.
James Lubitz has written: 'Medicare enrollment data for health planners' -- subject(s): Medicare
There is no penalty; providers are not required to accept Medicare or Medicaid.
Many of the physicians who on staff at the University of Texas Medical Branch are Medicare providers.
checking on the status of medicare application for Part B?
Medicare is a public health insurance program; it does not pay beneficiaries.[per Medicare.gov]"Your Initial Enrollment Period starts 3 months before you turn age 65 and lasts for 7 months. Except in certain cases, if you do not enroll in Medicare Part B during your Initial Enrollment Period, you will have wait until the next General Enrollment Period to enroll. General Enrollment Periods are between January 1 and March 31 each year. When March 31 falls on a non-business day, the General Enrollment Period is extended to the next business day. If you sign up for Medicare Part B during a General Enrollment Period, your coverage starts on July 1 of that year...."
Fall open enrollment is the best time to change medicare insurance plans. You can find out a lot of information about your different options by contacting a Medicare representative.
Medicare Part A covers hospital services. Medicare Part B covers services by other providers such as physicians.
Providers are not required to participate in either the Medicare or Medicaid program. In addition, providers are required to tell you when you present your Medicare or Medicaid cards that they do not accept the programs (generally this is on the paperwork where they ask for the insurance information). If they render treatment and you have presented your id cards prior to the visit (and they did not otherwise advise you or have you sign something that they don't participate) then contact Medicare at 1-800-Medicare to report the provider.
If you are late in enrolling in Medicare Part D, you may owe a a penalty. In 2013, the penalty was $31.17 and if you owe it, it will be added to your premium.