U.S. government debt has crossed the $40 trillion mark, an alarming milestone for economists who fear the nation's fiscal policy is spiraling out of control.

The threshold was passed after the Congressional Budget Office (CBO) reported earlier this month that deficits are now so large the U.S. Treasury is paying $3 billion a day in interest, totaling $963 billion between October 2025—when the 2026 fiscal year begins—and July 2026.

Treasury data for August 18 shows the closing balance for the day on public debt outstanding totaled $40.04 trillion.

Budget watchdogs have continually called on policymakers to get America's fiscal house in order, and the scale of the debt helps explain why the issue keeps resurfacing in Washington even when markets are calm. Proposals range from cutting annual federal deficits in half as a share of GDP—down from the current 6% to 3%—to calls to “cut up the credit cards” entirely. The White House itself has indicated it recognizes a problem, with President Trump suggesting tariffs or visa policy could help plug the budget gap. So far, data suggests it won't be enough.

With the country's debt-to-GDP ratio now north of 120%—a metric lenders will watch when analyzing the risk premium on loans to the U.S.—debt hawks are warning that the public is already paying the price and is only going to start feeling the squeeze more acutely.

“We are paying that bill”

Michael Peterson is the chairman and CEO of the Peterson Foundation, a nonpartisan organization dedicated to putting the U.S. on a more sustainable fiscal path. Speaking to Fortune as America hit the $40 trillion benchmark, Peterson explained that even if families don't receive a “bill in the mail” for the national debt, they're already paying it.

He explained: “When the U.S. borrows this much—and continues to borrow more and more—that drives up interest rates, which then increases household expenses because your mortgage goes up, your car loan, your credit card bills, and inflation more generally. So [we] may not get a bill at the end of the month for national debt, but [we] are paying that bill both in the form of taxes as well as an inflated level of expenses.”

While the mechanics of how debt may trickle down to individual households' finances are complicated, voters are nevertheless expressing concern about the topic as Washington heads into the midterms. In July, a Peterson Foundation study reported that 94% of voters are more likely to support a candidate with a plan to address the debt, including 95% of Democrats, 92% of independents, and 94% of Republicans.

“To anyone who cares about America, about democracy and our future, in my view, this is already a crisis,” Peterson said, “because the level of fiscal mismanagement is tragic. It is burdening every household today, it's laying more and more debt on our children and grandchildren, and that's not how America got to be the great country that it is.”

What gives?

The bull case for debt is reasonable. Firstly, despite years of warnings, there has yet to be a market meltdown sparked by debt.

Indeed, Treasury yields—the surest sign of confidence in U.S. borrowing and lending—are showing no signs of acute discomfort. At the time of writing, 30-year Treasuries sit above 5%, elevated in part by the uncertainty of Federal Reserve policy. The 10-year Treasury is sitting above 4.6% for a similar confluence of reasons.

But debt hawks point to other indicators that suggest the budget will have to give in one area or another.

Nancy Vanden Houten, lead U.S. economist at Oxford Economics, said in a recent note that “mandatory spending, including Social Security, Medicare, and interest on the debt, continue to see the most growth in spending. Fiscal year-to-date defense spending continues to creep higher as the war with Iran drags on; as of July, defense spending was up 5% y/y.”

A trade-off between two of those outlays seems to be on the books: the trust fund for Social Security is due to run dry in a little under eight years, and Medicare in a little under seven years, according to estimates by the Committee for a Responsible Federal Budget.

While “it's hard to pinpoint an exact moment in time or an exact program that will be in jeopardy, if you care about government programs and what the government can do to help society, defend our country, make sure the most vulnerable are protected, and take care of the elderly, the first thing you should do is put us on a more stable fiscal path so that all those programs are less in jeopardy,” Peterson said.

However, any cross-party agreement to examine or target borrowing in order to reduce the debt is yet to materialize, leaving the next budget fight likely to hinge on whether lawmakers can address the biggest spending buckets before they become more constrained. Peterson adds: “There's a lack of urgency that concerns me. Just because the financial markets were OK yesterday doesn't mean they're gonna be OK tomorrow. To just continue to cross your fingers and hope that we can get away with a completely irresponsible level of budgeting is not a reasonable way to lead our country.”

This story was originally featured on Fortune.com.