WASHINGTON (AP) — The deadline for Congress to increase the government’s borrowing limit is coming earlier than expected, moving up to about Nov. 5.

That means the issue likely must be addressed before House Speaker John Boehner, R-Ohio, leaves Congress at the end of October.

Three weeks ago, Treasury Secretary Jacob Lew issued a less precise timeline that was interpreted as mid-November or later, but he told top lawmakers in a letter Thursday that tax receipts have come in below estimates and payments into military retirement trust funds are higher than anticipated.

The Congressional Budget Office, which supplies estimates to lawmakers, said in August that the deadline would be about late November or early December.

Increasing the government’s borrowing limit above $18.1 trillion is needed to prevent a first-ever default on government obligations like interest payments and Social Security. The government has never failed to meet its obligations and a default would likely have severe effects on interest rates and the economy.

Since the limit was reset in March, Treasury has employed accounting maneuvers known as “extraordinary measures” to be able to continue to borrow. Those measures chiefly involve suspending payments into federal retirement funds.

“We now estimate that Treasury is likely to exhaust its extraordinary measures on or about Thursday, Nov. 5,” Lew wrote top lawmakers. “At that point, we would be left to fund the government with only the cash we have on hand, which we currently forecast to be below $30 billion.”

Congress last increased the debt limit in February 2014.

In 2011, Republicans used the need to increase the debt limit as leverage to force President Barack Obama to agree to spending cuts. But Obama has since refused to negotiate over the debt limit and last year’s increase passed largely on the votes of House and Senate Democrats.

The debt limit issue is but one element in a difficult matrix of issues facing Congress this fall. While Republicans controlling the House and Senate managed Wednesday to avert a shutdown by funding the government through Dec. 11, difficult negotiations over increasing the spending caps set in 2011 — as demanded by Obama — have only started.

Last week’s shocking announcement by Boehner that he is stepping down at the end of the month only complicates matters. So too do an ongoing set of leadership races to replace him and Speaker-in-waiting Kevin McCarthy, R-Calif. Boehner is leaving under pressure from tea party lawmakers unhappy that he wasn’t using a must-do temporary funding bill to “defund” Planned Parenthood.

The threat of a debt default is far more dangerous than a partial government shutdown and top Republicans such as Senate Majority Leader Mitch McConnell of Kentucky have promised it won’t happen. McConnell reluctantly voted to increase the limit last year and will now have to recruit more Republicans to join him since there are fewer Senate Democrats after last year’s midterm landslide.

“The treasury secretary’s letter is a stark warning of the stakes of Republicans’ calendar of chaos,” said House Minority Leader Nancy Pelosi, R-Calif. “Failure to protect the full faith and credit of the United States would have a devastating impact on hardworking families across the country — including tumbling retirement savings and rising interest rates for student loans, mortgages, credit cards and car payments.”

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