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Story highlights

The House will vote again on tax bill Wednesday morning

Senate rules means some provisions will be taken out

It's called the 'Byrd Bath' after a former Democratic senator

(CNN) —  

House Republicans applauded and cheered after they voted for their long-anticipated tax reform plan Tuesday.

But just hours later, it was revealed they’d have to do the vote all over again Wednesday.

That’s because of an arcane Senate procedure known as a “Byrd Bath,” where legislation undergoes a review to make sure it complies with the so-called Byrd rule.

The Senate parliamentarian ruled Tuesday afternoon that some changes will need to be made to the House version to make it comply with the Byrd rule, so the Senate will vote on the amended bill Tuesday night, then send it back to the House for a vote Wednesday morning.

This isn’t a huge surprise. It was expected that some changes might have to be made, and the House vote Wednesday won’t be considered a big deal.

Does every bill go through this process?

Nope.

Byrd rules only apply to legislation that’s being passed through a process known as budget reconciliation. Reconciliation allows the Senate to pass a bill with just a simple majority (51 votes) and bypass a filibuster, but the process has a strict set of rules. Under reconciliation, Republicans have to prove that everything they are including in their tax reform bill has an impact on the budget and not just an “incidental” one.

They can only use the process sparingly, and Republicans already tried using it when they unsuccessfully tried to pass a repeal of the Affordable Care Act, also known as Obamacare, earlier this year.

What is it?

The Byrd rule is named after the late Democratic Sen. Robert Byrd of West Virginia, who came up with the rule to stop either side from abusing the reconciliation process and trying to use it to just pass legislation that avoids a filibuster.

Here are the requirements:

1. Supporters of the proposal have to prove that the bill in question either increases revenues or reduces spending.

2. That those changes are not merely “incidental.”

3. That all the changes are within the jurisdiction of the committees outlined in the reconciliation instructions.

4. Senators for their proposal have to achieve at least the same amount of savings as the House bill did.

5. The proposal cannot have any impact on Social Security.

6. The provision must not increase spending or decrease revenues outside of the budget window if you want it to be permanent.

So how is the tax bill changing?

The Senate will strip out provisions that were in the House bill, including a provision that would allow the use of tax-free college savings accounts for home-school expenses.

The changes also strip part of the criteria used to determine whether the endowments of private universities are subject to the legislation’s new excise tax.

CNN’s Deirdre Walsh contributed to this report.