Tax cuts are not cheap, so when closing so-called loopholes left House Republican tax writers short of their budget target, they dipped into their grab bag of budget and timing tricks.

“Once you set that cap in reconciliation instructions, it has to fit,” Ways and Means member Carlos Curbelo of Florida said. “So the entire bill is designed to meet the instructions that both chambers passed.”

Republican congressional leaders are using the budget reconciliation process to consider the tax package, which allows them to bypass Senate procedural roadblocks. The catch is the legislation must adhere to parliamentary budget rules. 

The budget reconciliation instructions for the tax overhaul allow the measure to increase the deficit by $1.5 trillion over 10 years. The House bill would cost $1.4 trillion over 10 years, according to the Joint Committee on Taxation’s estimate.

House Republicans didn’t use nearly as many revenue-boosting mechanisms as they could have to improve the score because they believe economic growth will ultimately offset any static revenue losses. But the House faces fewer constraints than the Senate will.

Watch: Rep. Larson’s Fiery Condemnation of Tax Bill Process

The Senate’s budget reconciliation rules mandate that any policy that is to be made permanent under the measure not add to the deficit outside the 10-year budget window, meaning it must be fully offset.

Since it was Senate Republicans that first came up with the $1.5-trillion-deficit-adding instruction, they appear to acknowledge that full permanency is likely an unachievable goal.

But the closer Republicans want to get to that goal, the more so-called budget gimmicks they may need to employ.

Here are some maneuvers the House used to fit its tax bill into the $1.5 trillion hole that the Senate will likely look to as well.

Delaying start dates

Delaying the start of or phasing in provisions that lose money minimizes revenue loss within the 10-year budget window because it effectively hides some of the costs in those so-called out years.

This isn’t widely used in the House bill because chamber lawmakers know the second-decade costs will eventually be revealed to ensure the tax bill complies with reconciliation rules.

But one place House tax writers did employ this tactic is notable, and that is in repealing the estate tax after 2023.

During those intervening six years, the exemption for the amount of property not subject to the estate tax is doubled from $5 million to $10 million.

Both changes — doubling the exemption and then repealing the tax altogether — would cost $172.2 billion over 10 years, according to the JCT.

But delaying the repeal would limit the cost in the early years. The average cost of the provision over the first six years, when the estate tax is still in place but with a higher exemption, would be $8.6 billion per year, according to the JCT.

In the last four years of the budget window, when the repeal is in effect, the average cost of the provision would be $30.1 billion per year.

The Senate, which doesn’t have the luxury of ignoring the cost outside the 10-year budget window because of the reconciliation rules, is considering keeping the estate tax. That’s likely in large part because of cost, but also possibly for reasons of optics — repealing the estate tax could be seen as a tax cut for the wealthy.

The House seems to have kept the Senate constraints in mind, but not for this provision. Why? Because opposition to the estate tax is conservative orthodoxy and a bill keeping it would likely not have enough Republican votes to pass the House.

Watch: Rep. Reed Stacks Tax Code Books at Markup

Early expirations

Another way to save money is to let provisions expire within the 10-year budget window. This way, Republicans don’t have to worry about adding to the deficit in the out years, which, under reconciliation, would render certain provisions temporary anyway.

One provision that Republicans would let expire is full and immediate expensing of certain assets.

The bill would allow businesses to write off 100 percent of their capital investments for five years, after which current expensing rules would return absent congressional action to extend this provision.

The first five years of full and immediate expensing would cost $84.3 billion, according to the JCT. But after that, the provision becomes a revenue raiser, lowering the total 10-year cost to $25 billion.

The tax code already offers immediate expensing for small businesses under Section 179. Republicans propose expanding Section 179 expensing but that expansion would also expire after five years.

Specifically, the bill would increase the Section 179 expensing limit from $500,000 to $5 million and raise the current phaseout threshold for qualifying purchases from $2 million to $20 million.

The Section 179 expansion would cost money during the five years it is in effect — a total of $50 billion, according to JCT — and would raise money in the five years after it expires. Overall, the provision would cost $11.4 billion over 10 years.

On the individual side, Republicans created a family credit that would increase the current child tax credit from $1,000 to $1,600 per child and would add a $300 credit per parent and non-child dependent, the latter of which would expire after five years.

This, of course, would limit the cost. The family credit would cost an average of $56.5 billion per year over the first five years, and then in the later five years it would cost an average of $29.6 billion per year, according to the JCT. In total, it would cost $430.7 billion over 10 years.

Republicans say the intention is for Congress to renew the family credit in full when it comes time for the $300 credit to expire.

“That family credit is de facto permanent,” Curbelo said. “You can take it the bank. I know members on both sides will be very supportive of [keeping it].”

If Congress does later renew the credit or the expensing provisions, effectively new tax extenders, it’s unclear whether they would be paid for. In other words, letting them expire after five years is just to avoid having to offset the full cost.

Capping and indexing

Other techniques to limit revenue losses include capping deductions. For example, the bill would limit the deduction for state and local property taxes to $10,000 and the mortgage interest deduction to interest paid on the first $500,000 of new mortgages.

The bill also plays around with indexing in ways to save money. For example, the property deduction cap, among other tax benefits, is not indexed to inflation, which would limit the cost.

For provisions that are indexed, the bill changes the way the tax code measures inflation. Under current law, adjustments are made using the consumer price index, which, according to the Committee for a Responsible Federal Budget, can overstate inflation because it fails to account for the fact that when prices of similar goods change, consumers often switch to cheaper options.

Instead, the bill proposes using the chained consumer price index, which indexes spending and taxes to the rate of inflation over time. This method would slow the growth of tax benefits, resulting in a cheaper cost.

This lower inflation rate also has the effect of pushing people into higher tax brackets sooner, meaning more revenue for the government.

“Isn’t that why it’s there?” Ways and Means member Earl Blumenauer, an Oregon Democrat, asked during the committee markup of the bill Monday. “It’s a gimmick.”