Kansas City, Mo. — Tax-filing season officially begins next Monday. The Trump administration has ordered thousands of furloughed IRS employees back to work without pay to process returns, but hundreds are defying that order.

Shannon Ellis said she can no longer afford to go to work.

"It's too expensive to put gasoline in. We just don't drive a lot," she said.

As an IRS customer service representative, Ellis is one of the 800,000 federal workers furloughed without pay by the shutdown. She is among 36,000 from the IRS who the White House ordered back to their desks without pay last week.

Shannon Ellis CBS News

But Ellis declined, citing a union contract provision which allows her to miss work if it would be a "hardship" to show up. Not getting paid for her work qualifies.

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Ellis estimates 60 percent of her colleagues at the Kansas City office are taking advantage of the hardship exemption. That's a problem with the tax filing season almost upon us.

"At this point, I mean, I'm hoping there's enough employees to do the job. Our employees don't have the money to go to work. Period," she said.

Along with the IRS, the Transportation Security Agency is experiencing increased sick-outs. The same goes for meat inspectors at Department of Agriculture and guards at federal prisons.

The shutdown hits the lower paid workers at the IRS who process tax refunds the hardest. Some make $12 an hour and they'll miss a second paycheck Monday unless the government reopens.

Now the fate of Americans' tax refunds is up in the air. As the president of her union local, Ellis said she gets dozens of calls a day from worried IRS workers, including one of whom who attempted suicide.