Here’s something I didn’t know, from financial blogger Bruce Krasting (via John Ellis): Social Security tax receipts for the first half of 2010: $346.9 billion; Social Security benefits payments for the same period: $347.3 billion. Before this year, projections have always been that Social Security wouldn’t cross that line into negative cash flow for five years or so. Now it’s a reality. Congress has been spending Social Security’s positive cash flow for years. Now there’s no positive cash flow to spend.

To see how the negative trend has accelerated, consider the same figures for the first half of 2009: Social Security tax receipts were $366.0 billion and Social Security benefits payments were $334.3 billion.

A positive cash flow of $31.7 billion has disappeared in the course of just 12 months. Scary.