The national debt is really much larger than thought, argues Washington Post opinion writer Robert Samuelson.

Much larger.

The real national debt may be three times what’s generally believed, up to $31 trillion and 202 percent of gross domestic product (GDP), he writes. That’s because federal loan guarantees, both explicit and implicit, are typically not included in debt estimates, he points out. They are “off-budget.”

Editor's Note: Economist Warns: ‘Money From Heaven a Path to Hell.’ See Evidence.

Politicians love those off-budget programs because they let them spend without increasing taxes, he says. But they also create enormous risk for the government.

Samuelson counts the different ways to report the national debt.

Treasury debt held by the public, the most commonly cited figure, is $11.3 trillion, 73 percent of GDP for the 2012 fiscal year, the highest since the end of World War II.

Gross federal debt is $16 trillion, or 103 percent of GDP. This includes debt held by the public plus debt held by government trust funds like Social Security. Many economists don’t use the figure, as it’s like lending money to yourself.

Government loans and loan guarantees, as of 2011, amounted to $2.9 trillion, or 19 percent of GDP. Made to college students, farmers, veterans, small businesses and others, they are not included in the national debt, but the government is on the hook if borrowers default.

The government is also on the hook for $5.1 trillion of debt held by Fannie Mae and Freddie Mac, as well as $7.3 trillion of FDIC insurance protection on bank accounts.

If all the trust fund holdings, government loans and guarantees are included, the national debt is $31 trillion — 202 percent of GDP — almost three times the conventional $11 trillion estimate.

Fortunately, most borrowers will repay the loans — at least in normal times. But when the financial crisis and recession hit, the government had to rescue banks and take over Fannie Mae and Freddie Mac.

“Something similar could happen again,” Samuelson warns. “A deep downturn could cause a cascade of defaults on ‘off-budget’ guarantees that require on-budget bailouts. The lesson: We should reject new off-budget commitments and curb some that already exist.”

Government loan guarantees typically have very small costs to taxpayers but large economic benefits, according to the Center for American Progress.

On average, every $1 allocated to loan and guarantee programs generates more than $99 of economic activity, argue John Griffith, an analyst at the center, and Richard Caperton, the center’s director of clean energy investment.

The government usually does a good job in estimating risks and most programs cost less than originally estimated, they assert.

“Conservative critics often portray a world in which government bureaucrats haphazardly issue loans and loan guarantees without considering taxpayer exposure to risk,” they state. “That’s simply not the case.”

Editor's Note: Economist Warns: ‘Money From Heaven a Path to Hell.’ See Evidence.