• Home
  • Latest
  • Fortune 500
  • Finance
  • Tech
  • Leadership
  • Lifestyle
  • Rankings
  • Multimedia
Financedebt ceiling

The debt ceiling mystery: Why no one really knows exactly when the U.S. will run out of cash

Megan Leonhardt
By
Megan Leonhardt
Megan Leonhardt
Down Arrow Button Icon
Megan Leonhardt
By
Megan Leonhardt
Megan Leonhardt
Down Arrow Button Icon
October 1, 2021, 11:42 AM ET

There’s a bomb rapidly approaching detonation. Not a literal bomb, but a fiscal one in the form of the U.S. defaulting on its debts—and no one really knows exactly when it might detonate.

Since the U.S. hit its borrowing limit in August, the Treasury Department has been moving money around to try to cover its obligations, a process that’s called “extraordinary measures.” 

But this is only a short-term fix—Congress needs to raise the debt limit. If lawmakers fail to act, the Treasury will eventually run out of money, and the U.S. will need to make tough calls on who gets paid with the money available and what’s left to default.

After weeks of citing a mid-October deadline, U.S. Treasury Secretary Janet Yellen on Tuesday estimated that the Treasury Department would run out of money by Oct. 18 if Congress has not acted to raise or suspend the debt limit. “While this is our best estimate, the federal government’s cash flows are subject to unavoidable variability,” Yellen hedged. 

The Congressional Budget Office’s latest report on situation issued Wednesday failed to pinpoint a date at all, simply stating “if the debt limit remains unchanged, the Treasury’s ability to borrow using extraordinary measures will be exhausted, and it will most likely run out of cash near the end of October or the beginning of November.”

Why is it so hard for the U.S. government to calculate when the money runs out? 

The timing of federal government revenues and spending on a daily basis is highly uncertain. While some expenses like Social Security are pretty predictable, others like Medicaid claims are more dynamic. There’s less predictability around when states are going to submit claims and for how much. The effects of the COVID-19 pandemic and federal disaster relief have exacerbated that unpredictability, says Mark Zandi, chief economist of Moody’s Analytics.

“The pandemic has scrambled the timing of tax payments and outlays related to pandemic support,” Zandi tells Fortune. “The timing of when the federal government cuts a check to help with disaster relief is also difficult to know.”

The Treasury Department, for instance, is still disbursing pandemic relief funds to states and localities, stimulus payments to eligible households, and advanced child tax credit payments, among others, says Bernard Yaros, an assistant director and economist at Moody’s Analytics. “This adds another element of uncertainty to forecasting the default date.”

Outlays for the Small Business Administration’s Paycheck Protection Program loan forgiveness, for example, are particularly varied. There’s no outlay from the government until a small business applies for forgiveness and the forgiveness is approved. Businesses typically have about 10 months after their covered period ends to file for forgiveness.

Additionally, if the Delta variant were to meaningfully slow the economic recovery, it would increase certain Treasury payments and reduce revenues, which would then accelerate the default date, Yaros told Fortune. 

Yet even in normal times, forecasting the default date is always full of uncertainty, Yaros says. Each month, there are millions of withdrawals from—and deposits into—the Treasury’s account at the Federal Reserve where it maintains its cash balance, Yaros says. 

“The Treasury doesn’t know with certainty exactly how much is going to come in each day, in terms of tax revenues, nor do they know exactly how much is going to go out each day in payments,” says Paul Van de Water, senior fellow with the Center on Budget and Policy Priorities. 

While some expenses like Social Security are pretty predictable, others like Medicaid claims are more dynamic. There’s less predictability around when states are going to submit claims and for how much. 

With all of this uncertainty, Zandi believes that Yellen is likely being conservative in her estimate of Oct. 18 as the drop-dead date. “That is understandable,” Zandi adds, “given the cataclysmic costs of lawmakers misjudging and not acting in time to increase or suspend the debt limit.”

More finance coverage from Fortune:

  • She ran Bumble’s IPO while being treated for breast cancer. Now she’s becoming a CEO
  • Home insurance rates for millions of Americans are about to go up
  • Funding paid leave and child care narrows gender wage gap, says new report
  • Why aren’t interest rates going up? There are 3 possible reasons
  • A supply shock is about to hit the housing market—the question is how big?

Subscribe to Fortune Daily to get essential business stories straight to your inbox each morning.

About the Author
Megan Leonhardt
By Megan Leonhardt
LinkedIn iconTwitter icon
See full bioRight Arrow Button Icon

Latest in Finance

Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025

Most Popular

Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Fortune Secondary Logo
Rankings
  • 100 Best Companies
  • Fortune 500
  • Global 500
  • Fortune 500 Europe
  • Most Powerful Women
  • Future 50
  • World’s Most Admired Companies
  • See All Rankings
Sections
  • Finance
  • Fortune Crypto
  • Features
  • Leadership
  • Health
  • Commentary
  • Success
  • Retail
  • Mpw
  • Tech
  • Lifestyle
  • CEO Initiative
  • Asia
  • Politics
  • Conferences
  • Europe
  • Newsletters
  • Personal Finance
  • Environment
  • Magazine
  • Education
Customer Support
  • Frequently Asked Questions
  • Customer Service Portal
  • Privacy Policy
  • Terms Of Use
  • Single Issues For Purchase
  • International Print
Commercial Services
  • Advertising
  • Fortune Brand Studio
  • Fortune Analytics
  • Fortune Conferences
  • Business Development
  • Group Subscriptions
About Us
  • About Us
  • Editorial Calendar
  • Press Center
  • Work At Fortune
  • Diversity And Inclusion
  • Terms And Conditions
  • Site Map
  • About Us
  • Editorial Calendar
  • Press Center
  • Work At Fortune
  • Diversity And Inclusion
  • Terms And Conditions
  • Site Map
  • Facebook icon
  • Twitter icon
  • LinkedIn icon
  • Instagram icon
  • Pinterest icon

Latest in Finance

How to get out of debt: 9 proven strategies that actually work
Personal Financedebt relief
How to get out of debt: 9 proven strategies that actually work
By Joseph HostetlerApril 10, 2026
3 hours ago
Amazon is still paying Jeff Bezos an $80,000 yearly salary—but $1.6 million for travel and security
Big TechCEO salaries and executive compensation
Amazon is still paying Jeff Bezos an $80,000 yearly salary—but $1.6 million for travel and security
By Marco Quiroz-GutierrezApril 10, 2026
3 hours ago
A laptop screen shows World Liberty Financial's website
CryptoCryptocurrency
Trump-backed World Liberty Financial tokens hit all-time low on reports of insider loans
By Jack KubinecApril 10, 2026
4 hours ago
Iran is demanding tankers in the Strait of Hormuz pay tolls in crypto: What we know so far
CryptoIran
Iran is demanding tankers in the Strait of Hormuz pay tolls in crypto: What we know so far
By Ben WeissApril 10, 2026
4 hours ago
scott bessent
CybersecurityFederal Reserve
The AI that found 27-year-old vulnerabilities no human ever caught before just forced an emergency meeting with every major Wall Street CEO
By Jake AngeloApril 10, 2026
6 hours ago
man leaning against t shirt stand
EconomyInflation
Inflation goes up by a whopping monthly rate of nearly 1%—and it’s hitting you at the grocery store and gas station
By Catherina Gioino and Eva RoytburgApril 10, 2026
6 hours ago

Most Popular

The U.S. government is spending $88 billion a month in interest on national debt—equal to spending on defense and education combined
Economy
The U.S. government is spending $88 billion a month in interest on national debt—equal to spending on defense and education combined
By Fortune EditorsApril 9, 2026
1 day ago
A Meta employee created a dashboard so coworkers can compete to be the company's No. 1 AI token user—and Zuckerberg doesn't even rank in the top 250
AI
A Meta employee created a dashboard so coworkers can compete to be the company's No. 1 AI token user—and Zuckerberg doesn't even rank in the top 250
By Fortune EditorsApril 9, 2026
2 days ago
Mark Cuban admits he made a mistake letting go of the Mavericks: 'I don't regret selling. I regret who I sold to'
Investing
Mark Cuban admits he made a mistake letting go of the Mavericks: 'I don't regret selling. I regret who I sold to'
By Fortune EditorsApril 9, 2026
1 day ago
Schools across America are quietly admitting that screens in classrooms made students worse off and are reversing years of tech-first policies
Innovation
Schools across America are quietly admitting that screens in classrooms made students worse off and are reversing years of tech-first policies
By Fortune EditorsApril 10, 2026
15 hours ago
'I hate working 5 days': Zoom CEO says traditional work schedules are becoming obsolete—and predicts a 3-day workweek by 2031
Success
'I hate working 5 days': Zoom CEO says traditional work schedules are becoming obsolete—and predicts a 3-day workweek by 2031
By Fortune EditorsApril 9, 2026
1 day ago
Gen Z doesn't want your full-time job. They want several part-time roles, and it's reshaping the entire workforce
Success
Gen Z doesn't want your full-time job. They want several part-time roles, and it's reshaping the entire workforce
By Fortune EditorsApril 9, 2026
2 days ago

© 2026 Fortune Media IP Limited. All Rights Reserved. Use of this site constitutes acceptance of our Terms of Use and Privacy Policy | CA Notice at Collection and Privacy Notice | Do Not Sell/Share My Personal Information
FORTUNE is a trademark of Fortune Media IP Limited, registered in the U.S. and other countries. FORTUNE may receive compensation for some links to products and services on this website. Offers may be subject to change without notice.