Thousands of IRS employees are expected to lose their jobs as Elon Musk's Department of Government Efficiency, or DOGE, continues widespread cuts to federal spending.

The move comes roughly three weeks since the opening of tax season and could impact millions of taxpayers who will file before the April 15 deadline, experts say.

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IRS funding has been targeted by Republican lawmakers since former President Joe Biden approved $80 billion for the agency via the Inflation Reduction Act, or IRA, in 2022.

The IRS layoffs have targeted probationary workers with less than one year of service -- or longer in some cases. There were an estimated 15,000 probationary employees at the agency, many who were hired via IRA funds, according to a lawsuit filed by the National Treasury Employees Union and others on Feb. 12.

An estimated 6,000 to 7,000 IRS workers may be impacted, according to reporting from CBS News and the Associated Press.

The U.S. Department of the Treasury didn't respond to CNBC's request to confirm these numbers.

These mid-season staffing cuts could significantly impact filers, experts warn. So, with major IRS changes underway, here are some key things to know.