Benefits for older Americans — especially through Social Security and Medicare — account for the largest part of federal spending today and for the lion’s share of the spending growth that will occur in coming decades without changes in policies. That growth is not surprising: With baby boomers moving into retirement, the number of beneficiaries of those programs is surging. Indeed, in the Congressional Budget Office’s current-law projections, all federal spending apart from Social Security, Medicare, defense and interest on the debt will amount to about the same percentage of gross domestic product 25?years from now that it did 25 years ago. At the same time, federal debt is now larger relative to the economy than at almost any point in our history and is on an upward long-term trajectory. Therefore, cuts in Social Security or Medicare benefits, or increases in the taxes used to finance those programs, will almost certainly be needed to put federal debt on a sustainable path.
Elmendorf, Douglas. "A Fairer Approach to Fiscal Reform." The Washington Post, October 11, 2015.