Ryan says his Medicare voucher plan is just like the Federal Employees Health Plans, but Van Hollen says it is not in one important aspect, 'Fair Share.' Ryans's voucher would not keep up with inflation--even if a senior could get health insurance from a private company. I expect the health insurance industry will not support Ryan's vouchers for Medicare and will work to see if does not pass.)
The Government's share of premiums paid is set by law. Amendments to the FEHB law under the Balanced Budget Act of 1997 (Public Law 105-33, approved August 5, 1997) authorized a new formula for calculating the Government contribution effective with the contract year that begins in January 1999. This formula is known as the "Fair Share" formula because it will maintain a consistent level of Government contributions, as a percentage of total program costs, regardless of which health plan enrollees elect.
http://www.opm.gov/insure/health/reference/handbook/fehb03.asp