Lawmakers have just under a year and a half to rewrite the U.S. tax code—otherwise it will rewrite itself, with far-reaching consequences for your tax returns and the economy.

That’s because numerous tax cuts and changes signed by former President Donald Trump and an important one by President Joe Biden are set to expire by the end of 2025. These include key income tax provisions in the Tax Cuts and Jobs Act of 2017 and a significant increase in health care subsidies in the Inflation Reduction Act of 2022.

When that day comes, everything will go back to the way it was before these laws were passed, unless Congress extends or changes the provisions in question. Either way, people’s household finances and the economy as a whole could face major upheaval, with the outcome depending heavily on how each party performs in the upcoming November elections.

“You need to pay attention to some of these things, even if you haven’t done so before, because these are both big and fixed changes,” said Mark Steber, chief tax information officer at accounting firm Jackson-Hewitt, in an interview with Investopedia. “If they don’t do something, they’ll go away and you’ll pay more. If they change something … it’s going to affect you, for better or for worse, and you can’t hide from it.”

As the nonpartisan Tax Foundation put it in a recent report, “The vast majority of Americans will face higher and more complicated taxes” if lawmakers do not act.

These are some of the specific things that will be lost if they are not renewed:

Income taxes would be higher

The TCJA lowered marginal tax rates for most income levels. Here’s how they would change when the TCJA expires, for an individual taxpayer:

The standard deduction would be reduced

One of the biggest changes the TCJA brought was the expansion of the standard deduction. For single filers, for example, the deduction was nearly doubled from $6,500 to $12,000, and for married couples filing jointly, it was increased from $13,000 to $24,000. It also eliminated personal exemptions, reducing your tax burden for each person in your household.

At the same time, the law reduced the value of some special itemized deductions, causing more people to take the simpler standard deduction rather than seek special tax breaks.

In 2021, only 9.8% of taxpayers claimed itemized deductions, compared to 30.6% in 2017.

If the TCJA were to expire, the standard deduction would be reduced to the old level and then adjusted for inflation. It would also reinstate personal exemptions. This means more people would benefit from itemizing, which would make calculating taxes more complex.

Healthcare would become more expensive

In addition to Trump’s tax cuts, a major policy change by Biden will expire at the end of 2025: an amendment to the Affordable Care Act that significantly reduces premiums for health insurance purchased on government marketplaces.

Biden’s changes allowed people earning more than 400 percent of poverty income to apply for tax credits that offset the cost of health insurance purchased on ACA marketplaces. The overall effect was a reduction in premiums of about $700 a year in 2024 for the average person enrolled in an ACA plan, the Department of Health and Human Services estimated. According to a White House estimate, families saved an average of $2,400 per year.

If the law were to expire, about 3.8 million fewer people would have insurance coverage by 2034, the Congressional Budget Office predicted.

The child allowance would be lower

The TCJA doubled the maximum amount of the child tax credit to $2,000 per child and made it available to higher-income households. When the TCJA expires, the amount will go back to $1,000, and the amount of the tax credit would be reduced for married couples earning $110,000 or more, from $400,000 under current law.

Vice President Kamala Harris, the presumptive Democratic nominee, has put forward a plan to further expand the child tax credit, matching the temporary 2021 child tax credit expansion passed as part of the American Rescue Plan pandemic relief bill. This year, the tax credit was $3,000 per child, or $3,600 for children under 6, and was paid out in monthly checks. She also proposed adding a provision for parents of newborns, increasing the amount of the tax credit to $6,000 for the first year of a child’s life.

On the Republican side, vice presidential candidate JD Vance said the Trump campaign would increase the child tax credit to $5,000 per child.

Millionaires would pay more for their inheritance

The TCJA doubled the amount people could receive from inheritances without paying the 40% estate tax, from $5 million to $10 million. The current inflation-adjusted amount of $13 million would be reset to the old amount of $5 million and then adjusted for inflation.

Residents of high-tax states would receive tax relief

Some provisions of the TCJA actually increased taxes rather than cut them. One of these was a cap on state and local taxes (SALT), which primarily affected higher earners in states with high income and property taxes.

The TCJA set a $10,000 cap on the amount that state and local taxes can be deducted from federal taxes for taxpayers who itemize their deductions. The cap would disappear when the TCJA expires.

The wealthy are likely to be hit hardest

The wealthiest taxpayers have the most to lose when the tax cuts expire. According to an analysis by William Gale, a senior fellow at the Urban-Brookings Institute Tax Policy Center, a nonpartisan think tank, the bottom fifth of earners received a tax cut of $60 per year under the TCJA. The middle fifth got a $930 benefit, while the top 20 percent got $7,640 and the top 1 percent got $51,000.

“These tax cuts were primarily targeted at high-income households,” Gale said.

For this reason, the TCJA’s tax cuts likely provided only a modest boost to the economy and consumer spending, since wealthier households tend to spend a smaller share of their income than lower-income households, according to an analysis by Gale.

Democrats want to roll back the TCJA’s benefits for the wealthy while keeping provisions that benefit low-income earners. In a recent interview with Politico, Harris said she would not raise taxes on people earning less than $400,000 a year, continuing a Biden promise.

An expansion of all areas would be costly

If Congress were to simply extend the laws and leave everything as it is, that would also have consequences and would increase the national debt to $34 trillion. According to an analysis by Gale, the permanent implementation of the Trump tax cuts alone would cost $3.8 trillion over the next decade – which would put an even greater strain on the federal budget, which, according to the Congressional Budget Office, already spends more on interest payments than on the military.

“The big policy challenge and the political challenge that comes with it is the enormous cost of all of this,” Garrett Watson, senior policy analyst at the Tax Foundation, told Investopedia. “Even if you just extend the tax cuts for the non-rich, you’re looking at a cost of $2 trillion to $2.5 trillion over 10 years.”

In recent years, Republicans and Democrats have often compromised on spending policies: Democrats gave Republicans the tax breaks for corporations and the wealthy that they wanted, and Republicans gave Democrats the spending on social programs that they wanted, leading to ever-larger deficits.

As this debt becomes more expensive due to higher interest rates, more and more experts are warning that larger budget deficits could pose a risk to the economy. And politicians are also taking note.

“The option of simply skipping the political compromises and opting for a deficit-financed tax cut will be much more difficult to implement this time, if it is even possible,” Watson said.