Regrettably, it's time to pay attention to the debt ceiling again. The temporary suspension of the limit passed in October runs out at the end of this week. And unlike before--when Treasury had a whole slew of options for buying time--this time will be different.

Because it's tax filing season, cash flows will be more volatile over the coming weeks as the government likely pays out more in refunds than it's getting in income. That means less breathing room for Treasury as it tries to come up with solutions to stave off default.

On top of this, one of the two major "extraordinary measures" that Treasury used last year--and that helped buy the government five months of extra time--is not available this year.

Last year when the country's borrowing authority expired, Treasury was able to free up money by deferring new investments in its civil-service disability and retirement fund.

Here's how it works: Throughout the year, securities in the fund mature, or interest is earned on the securities, and that money is credited to the fund. In an unusually dire situation where Treasury has run out of borrowing authority, it's possible for the government to defer those credits temporarily and apply that money towards issuing more debt to pay its bills. It's just a way of rearranging things for a while until Congress raises the debt ceiling.

This year, though, this major tool won't be available. By a fluke of timing, there isn't money scheduled to be credited to the fund in the coming weeks. And so Treasury has less time to work with.

When will the clock run out exactly? The timing with the tax season makes it hard to pin down an exact date. In its latest analysis, the Bipartisan Policy Center estimates that the government will not be able to meet all of its obligations sometime between Feb. 28 and March 25. The BPC says default will mostly likely occur “on or in the days before March 14.”

This is a big difference from last year, when Treasury was able to keep things afloat from May to October. This time around, Sec. Jack Lew is working with weeks, not months. And the House GOP is still deciding on its strategy.