Paul Krugman: Long-run budget math

Some commenters have asked for more about Social Security’s role in the long-run budget problem, and in particular an explanation of my assertion that the Beltway obsession with Social Security reflects ignorance. So here’s a quick, informal explanation.

Start with the current position. Last year, federal spending on Social Security, Medicare, and Medicaid was 8.5 percent of GDP, equally divided between Social Security and the health care programs. Dismal long-run projections, like those of the GAO, have this total rising by 10 percentage points of GDP by mid-century.