• 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
  • World's Most Admired Companies
  • See All Rankings
  • Lists Calendar
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
  • Press Center
  • Work At Fortune
  • Terms And Conditions
  • Site Map
  • About Us
  • Press Center
  • Work At Fortune
  • Terms And Conditions
  • Site Map
  • Facebook icon
  • Twitter icon
  • LinkedIn icon
  • Instagram icon
  • Pinterest icon

Latest in Finance

Current refi mortgage rates report for May 11, 2026
Personal FinanceReal Estate
Current refi mortgage rates report for May 11, 2026
By Glen Luke FlanaganMay 11, 2026
1 hour ago
Current ARM mortgage rates report for May 11, 2026
Personal FinanceReal Estate
Current ARM mortgage rates report for May 11, 2026
By Glen Luke FlanaganMay 11, 2026
1 hour ago
Mortgage rates today, May 11, 2026
Personal Financemortgages
Mortgage rates today, May 11, 2026
By Glen Luke FlanaganMay 11, 2026
1 hour ago
voters in line
EconomyElections
Forget the Rust Belt or the Sun Belt. The ‘Wired Belt’ may be the next frontier of American political power
By Jake AngeloMay 11, 2026
2 hours ago
Markets sell off as U.S.-Iran ceasefire plans go nowhere, leaving Trump with military options to reopen the Strait of Hormuz
EnergyIran
Markets sell off as U.S.-Iran ceasefire plans go nowhere, leaving Trump with military options to reopen the Strait of Hormuz
By Jason MaMay 10, 2026
10 hours ago
Mah Sing sees natural ‘spillovers’ from Malaysia’s strong growth, as the conglomerate bets on premium residences and data centers
Real EstateSoutheast Asia 500
Mah Sing sees natural ‘spillovers’ from Malaysia’s strong growth, as the conglomerate bets on premium residences and data centers
By Angelica AngMay 10, 2026
11 hours ago

Most Popular

‘This is the way’: Elon Musk endorses Warren Buffett’s famed 5-minute plan to fix the national debt
Economy
‘This is the way’: Elon Musk endorses Warren Buffett’s famed 5-minute plan to fix the national debt
By Jacqueline MunisMay 10, 2026
20 hours ago
OpenAI CEO Sam Altman says Gen Z and millennials are using ChatGPT like a 'life advisor'—but college students might be one step ahead
Tech
OpenAI CEO Sam Altman says Gen Z and millennials are using ChatGPT like a 'life advisor'—but college students might be one step ahead
By Sydney LakeMay 10, 2026
20 hours ago
'Employers are increasingly turning to degree and GPA' in hiring: Recruiters retreat from ‘talent is everywhere,’ double down on top colleges
Future of Work
'Employers are increasingly turning to degree and GPA' in hiring: Recruiters retreat from ‘talent is everywhere,’ double down on top colleges
By Jake AngeloMay 9, 2026
2 days ago
Red flag test: former CEO explains why he rejects job candidates who say they can start right away
Success
Red flag test: former CEO explains why he rejects job candidates who say they can start right away
By Orianna Rosa RoyleMay 9, 2026
2 days ago
Trump thinks he's flying to Beijing with leverage. China spent 6 years making sure he doesn't have any
Commentary
Trump thinks he's flying to Beijing with leverage. China spent 6 years making sure he doesn't have any
By Steve H. HankeMay 10, 2026
22 hours ago
Ted Cruz says the quiet part out loud: Trump accounts are Social Security personal accounts as GOP senator reveals 'dirty little secret'
Politics
Ted Cruz says the quiet part out loud: Trump accounts are Social Security personal accounts as GOP senator reveals 'dirty little secret'
By Jason MaMay 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.