The Medicare program provides subsidized medical insurance for the elderly and for some disabled people. In 2013, Medicare had about 51 million beneficiaries. Gross spending (excluding administrative costs that are subject to appropriation) for the program was $585 billion. (Net spending, which has beneficiaries’ payments of premiums and some other receipts subtracted out, was $492 billion.) CBO anticipates that Medicare spending will rise rapidly over the next decade, spurred by the retirement of the baby boomers. The agency’s work on Medicare includes projections of future program spending, cost estimates of specific legislative proposals, and a range of analyses of policy options and issues affecting the program.