(CNN) The Internal Revenue Service is bringing back tens of thousands of additional federal employees with less than two weeks before tax filing season begins.

The federal tax collector said Tuesday in an undated government shutdown plan that it would recall an additional 36,000 federal employees, bringing the total number of those working at the IRS during the partial government shutdown to more than 46,000, or roughly 57% of the workforce.

The move will allow Americans to get their tax refunds on time, but at the expense of the IRS employees, most of whom won't be paid.

Only 809 federal employees in two specific areas of the agency will get their paychecks because their operations are funded by user fees.

The National Treasury Employees Union, which represents roughly 70,000 IRS workers around the country, said Tuesday that the executive branch can't continue to force more and more employees to show up in exchange for an IOU.

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