After congressional Republicans passed their massive tax reform bill late last year, Americans felt the impact quickly.

Republicans passed their tax package in mid-December, and the bill’s statutory language meant it went into effect on January 1, 2018. The sweeping overhaul of taxes reduced rates for corporations and individuals (although individual tax cuts will eventually expire) and repealed the Affordable Care Act’s individual mandate, effectively kicking 13 million people off their insurance, according to the Congressional Budget Office.

But Americans likely won’t see a big difference in their tax returns this spring; the proposed cuts in the bill will show up when most people file in 2019.

“When they’ll really see the difference is a year from March and April,” said Marc Goldwein, senior policy director for the bipartisan Committee for a Responsible Federal Budget.

Related 4 winners and 4 losers from the Republican tax bill

Still, the new tax law will make more immediate changes, including to the amount of money employers withhold from their paychecks for tax purposes.

Beyond proposed cuts that will show up in people’s tax returns, there are much bigger implications and changes taking place down the line. The Republican tax law will cause the national deficit to increase by $1 trillion over the next decade. It will also let individual tax cuts expire after 10 years, meaning taxes on the middle class would eventually go up. Furthermore, some Republicans are advocating for the idea of raising tax rates if the tax bill doesn’t produce enough economic growth to stave off a deficit increase.

It’s hard to predict exactly how this would impact everyday Americans, but tax experts can say a few things with certainty: Older, wealthier Americans are going to benefit in the long run, while young Americans who work will be left footing the bill for years to come.

“It’s going to be a while before the full impact of this reveals itself,” said Eric Toder, co-director of the Urban Institute’s Tax Policy Center.

Indeed, some polling indicates most people haven’t noticed changes in their tax returns this year. A February Politico/Morning Consult poll found that 25 percent of registered voters said they have noticed an increase in their paycheck under the new tax law; 51 percent say they haven’t seen any change, and 24 percent aren’t sure.

Like the health care bill, the tax bill favors older, wealthier people

Around the time of the tax vote, Business Insider ran an analysis to estimate how much savings individual earners would see under the House GOP tax bill (which was not the final bill that was passed). They estimated that a single, childless taxpayer making $25,000 per year would see an average of $200 in savings, a taxpayer making $75,000 annually would see about $2,000 in yearly savings, and a taxpayer making $175,000 per year would see about $4,200 in savings.

But the plan the House and Senate agreed on and passed together in December would see those individual tax cuts eventually expire, while corporate tax cuts stay permanent.

“Basically, the individual income tax reverts to current law for tax year 2026 and beyond,” Goldwein said. “People get eight years of tax reform.”

With the corporate tax rate getting slashed from 35 percent to 21 percent and staying permanent, corporations are the big winners from the GOP tax cuts. But on the individual side, older and wealthier people also get a victory. Multiple analyses show that poorer Americans will lose out under the bill because individual tax cuts will eventually be phased out and the individual mandate will be repealed, causing an estimated 13 million people to lose health insurance, according to the nonpartisan Congressional Budget Office.

As Vox’s Dylan Matthews reported:

The CBO breaks down the billions of dollars in annual changes to spending and tax revenue by income group, up to people making more than $1 million. What they find is that while the rich as a group benefit each year (as do people making more than $75,000, on aggregate) the desperately poor, earning $10,000 or less a year, lose out consistently — and by 2021, people earning $40,000 a year or less start losing out as well.

Corporate tax cuts will trickle down to shareholders and investors, and therefore be a boost to older, wealthier retirees who make their money from investment earnings rather than wages. Younger people, and people who must work for a living, will eventually see their tax cuts expire and will have to deal with consequences if the national deficit grows.

“There’s a redistribution of burden from the old to the young,” Toder said.

Future generations stand to lose much more, especially if the tax cuts balloon the national deficit as much as they are projected to. Eventually, someone has to pay for the cost of these steep cuts, whether that’s through increased future taxes, cutting spending or entitlement programs, or a mix of all three.

“One way or another, those tax cuts are going to have to be paid back, [and] it’s going to be skewed toward future generations,” Goldwein said. “If I’m a betting man, I don’t think it’s going to turn out well for the poor. But all I can say with certainty is that younger generations are going to pay more relative to how much they’re getting in the tax cut.”