As we reported last year, Medicare's financial difficulties come sooner—and are much more severe—than those confronting Social Security. While both programs face demographic challenges, rapidly growing health care costs also affect Medicare. Underlying health care costs per enrollee are projected to rise faster than the earnings per worker on which payroll taxes and Social Security benefits are based. As a result, while Medicare's annual costs were 3.2 percent of Gross Domestic Product (GDP) in 2008, or about three quarters of Social Security's, they are projected to surpass Social Security expenditures in 2028 and reach 11.4 percent of GDP in 2083.

The projected 75-year actuarial deficit in the Hospital Insurance (HI) Trust Fund is now 3.88 percent of taxable payroll, up from 3.54 percent projected in last year's report. The fund again fails our test of short-range financial adequacy, as projected annual assets drop below projected annual expenditures within 10 years—by 2012. The fund also continues to fail our long range test of close actuarial balance by a wide margin. The projected date of HI Trust Fund exhaustion is 2017, two years earlier than in last year's report, when dedicated revenues would be sufficient to pay 81 percent of HI costs. Projected HI dedicated revenues fall short of outlays by rapidly increasing margins in all future years. The Medicare Report shows that the HI Trust Fund could be brought into actuarial balance over the next 75 years by changes equivalent to an immediate 134 percent increase in the payroll tax (from a rate of 2.9 percent to 6.78 percent), or an immediate 53 percent reduction in program outlays, or some combination of the two. Larger changes would be required to make the program solvent beyond the 75-year horizon.

The projected exhaustion of the HI Trust Fund within the next eight years is an urgent concern. Congressional action will be necessary to ensure uninterrupted provision of HI services to beneficiaries. Correcting the financial imbalance for the HI Trust Fund—even in the short range alone—will require substantial changes to program income and/or expenditures. B of the Supplementary Medical Insurance (SMI) Trust Fund, which pays doctors' bills and other outpatient expenses, and Part D, which pays for access to prescription drug coverage, are both projected to remain adequately financed into the indefinite future because current law automatically provides financing each year to meet next year's expected costs. However, expected steep cost increases will result in rapidly growing general revenue financing needs-projected to rise from 1.3 percent of GDP in 2008 to about 4.7 percent in 2083-as well as substantial increases over time in beneficiary premium charges.

It is expected that about one quarter of Part B enrollees will be subject to unusually large premium increases in the next two years. This occurs because it is projected that the other three-quarters of Part B enrollees will not be subject to premium increases in those years due to low projected Social Security benefit COLAs and a "hold-harmless" provision of current law that limits premium increases to the increase in Social Security benefits.