If you looked at the new CBO report on the budget, you may have noticed that federal spending this year will be $3.6 trillion.

In fact, federal spending this year will top $4 trillion. But virtually all reporters and budget wonks (including me) routinely use the lower number when discussing total federal spending. I don’t think the higher $4 trillion number even appears anywhere in the CBO report.

The $3.6 trillion figure is “net” outlays. But “gross” outlays, or total spending, is quite a bit higher. The difference is caused by “offsetting collections” and “offsetting receipts.” These are revenue inflows to the government that are netted against spending at the program level, agency level, or government-wide level. Some examples are national park fees, Medicare premiums, and royalties earned on mineral deposits. There are hundreds of these cash inflows to the government that offset reported spending.

Details on these revenue offsets can be found in Chapter 16 of OMB’s Analytical Perspectives. In fiscal year 2010, net federal outlays were $3.456 trillion, but gross outlays were $4.057 trillion. Thus, gross outlays were 17 percent larger than widely reported net outlays.

In FY 2011, OMB expects gross outlays to be about 15 percent larger than net outlays. Thus, gross outlays this year will be $4.1 trillion, compared to net outlays of $3.6 trillion. As a share of GDP, gross outlays will be about 27.3 percent of GDP, compared to net outlays of 23.8 percent.

Accounting for offsets in this manner is a long-standing convention, but it is one of the sneaky ways that Washington tries to hide its large intrusion into the economy. Certainly, the CBO and OMB should include more prominent presentations of gross outlays in their regular budget updates.

For citizens and reporters, a rule-of-thumb to remember is that total federal spending is 3 to 4 percentage points of GDP larger than usually reported by officials.