Mark your calendars for February 27.  

That’s the date Treasury Secretary Jacob J. Lew anticipates the Treasury Department will exhaust the extraordinary measures used to avert exceeding the federal debt limit past today.  

Lew made the announcement in letters sent Friday afternoon to the top four Congressional leaders.  

“Given the heightened variability of cash flows during tax season — which began last Friday, January 31 — it is difficult to forecast with any certainty when Treasury will exhaust its borrowing capacity. Based on our best and most recent information, however, we are not confident that the extraordinary measures will last beyond Thursday, February 27,” Lew wrote. “At that point, Treasury would be left with only the cash on hand and any incoming revenue to meet our country’s commitments.”  

Lew said it would not be easy to make accurate predictions about potential defaults after that date, since the government’s cash flow can vary widely during tax filing season.  

“Moreover, net daily expenditures for the government can be as high as $60 billion on certain days. If Treasury has insufficient cash on hand,it would be impossible for our nation to meet all of its obligations for the first time in history,” Lew wrote.  

He renewed previous calls by the Obama administration to act quickly to eliminate uncertainty. Speaker John A. Boehner, R-Ohio, said Thursday that House Republicans “are still looking for the pieces to this puzzle .”  

A debt limit hike may see House action as soon as Wednesday, according to a schedule released by the office of Majority Leader Eric Cantor, R-Va. But GOP leadership aides noted that the conference has yet to coalesce around a proposal to do so, still struggling to find a legislative add-on that can attract sufficient support.  

Senate Budget Chairwoman Patty Murray issued a statement earlier Friday noting the arrival of the extraordinary measures period after the suspension of the debt ceiling earlier.  

“There’s no reason to drag this out any longer. Republicans should accept that they’re not getting a ransom out of their brinkmanship and agree to do the right thing for our economy by allowing the United States to pay its bills on time,” the Washington Democrat said.  

Still, the expected Feb. 27 deadline means that lawmakers and Congressional aides probably will not cancel their President’s Day recess plans.  

Daniel Newhauser contributed to this report.