Payroll tax hikes are the only option.

In order to cover that deficit and meet its obligations to current retirees, Social Security has been withdrawing money from the Social Security trust funds. Under what the government's actuaries call "intermediate" economic assumptions, the trust funds will be able to cover the deficit until 2033. After that, paying all promised Social Security benefits will require increasing the payroll tax by 50%. Under what the government's actuaries call "pessimistic" economic assumptions, the Social Security trust funds will run out of money to pay promised benefits by 2029. After that, paying all benefits promised to today's young workers will require doubling the current payroll-tax rate. A recent study by researchers at Harvard and Dartmouth concludes that the Social Security actuaries have been consistently over-optimistic in their demographic and economic assumptions regarding the future fiscal solvency of Social Security.

Some think that, because Social Security is not currently in crisis, Congress can deal with the program's problems later. But if Congress waits until 2029 or 2033 to fix Social Security, policymakers will be left with very few options and will likely be forced to raise payroll taxes to unprecedented and harmful levels. If Congress acts sooner rather than later, however, it can restructure Social Security to make it solvent and secure in the long term.