A federal government shutdown might seem like a great way to save money: When agencies aren’t open, they aren’t spending tax dollars. But history shows us that closing the government actually costs more than keeping it open.

Shuttered parks can’t collect entrance fees. Furloughed workers will ultimately get paid for not showing up to work. And the government will wind up having to pay interest on missed payments to some contractors.

“There’s nothing good about this shutdown, from a fiscal or a budgetary standpoint,” said Michael A. Peterson, chairman of the Peter G. Peterson Foundation, which advocates fiscal prudence and federal debt reduction. “We’re absolutely not celebrating not spending money.”

Here are some ways that the shutdown raises costs for the federal government.

Federal employees will eventually get their salaries — for work they weren’t allowed to perform

As a general rule, when the government spends money on something, it’s better to get something in return. Paying someone to empty trash bins in parks is better than paying that same person to sit at home, while the trash piles up, and then paying more, later, to actually empty the trash.