The federal government could end up defaulting on its debt “sooner than anticipated," according to new projections, if capital gains revenue collected by the Internal Revenue Service continues to come in weaker than expected.

Authors from Goldman Sachs Economic Research wrote in a new note Tuesday that “weak tax collections so far in April suggest an increased probability that the debt limit deadline will be reached in the first half of June.” Their conclusion is based on weaker receipts through April 14 with full data expected in the coming weeks.

Similarly, analysts at Wrightson ICAP who track the issue closely are not ruling out the possibility of a June default. They note in an update this week that if tax data remains soft, “a June X-date might start to look like a significant risk without becoming our base case.”

Debt ceiling observers have been closely monitoring tax season for clues about how the ongoing debt ceiling crisis could play out in the coming weeks and months. Without a deal in Congress, the government is set to be unable to pay its bills in the coming months, which could have cascading effects that would almost surely rattle markets and, many fear, tip the economy into a recession.

At issue is if the IRS ends up collecting more than projected, it would marginally improve the U.S. government's books and delay the so-called X-date — when the government is unable to pay its bills and is forced to default — by a few weeks or months.

Experts are expecting much more clarity by early May, and the Goldman authors noted that there remains a strong chance that the government stays afloat until later in the summer. Still, either way, uncertainty is increasing and they say the the odds are increasing that Congress will need to reach a deal within weeks

Tuesday’s note from Goldman is a significant update from its estimate in February that targeted early to mid-August as the most likely deadline.

The Wrightson ICAP said it currently forecasts “the Treasury’s remaining fiscal resources...would run below $100 billion from June 6 to June 13.”

The sense is that, if the Treasury Department can stay afloat through June, additional tax receipts that are due in mid-June would give the government a bit more breathing room and delay a default until later in the summer — unless the tax revenue comes in weaker than expected in the coming days.

What observers are watching is the remainder of the April tax receipts — especially in capital gains. Goldman projects that a decline of 35% to 40% "would be consistent with an early June deadline" and added that their data so far shows receipts down 39% from last year.

Other analysts at other places that track the issue like the Congressional Budget Office and the Bipartisan Policy Center likely will release their own estimates in the coming weeks as the full picture from tax season becomes clearer.

Experts have long been focused on June as the first significant debt ceiling deadline. Earlier this year, Treasury Secretary Janet Yellen projected that "it is unlikely that cash and extraordinary measures will be exhausted before early June." She has not updated her projections in the months since.

The U.S. formally hit the debt limit on Jan. 19 with Yellen and her aides beginning a process known as "extraordinary measures" in response. Those accounting maneuvers essentially allow the government to move money around in the vast U.S. Treasury to stave off an actual default, but for only a limited time.

Meanwhile, in Washington D.C., talks stalled. On Monday, House Speaker Kevin McCarthy (R-CA) traveled to the New York Stock Exchange Monday to warn Wall Street of the growing chance lawmakers “will bumble into the first default in our nation’s history.”

Republicans are blaming the White House for the stalemate, while Biden officials have shot back that Congress needs to pass a simple increase in the debt ceiling and McCarthy is making demands that even Republicans can't agree on.

Ben Werschkul is Washington correspondent for Yahoo Finance.

Click here for politics news related to business and money

Read the latest financial and business news from Yahoo Finance

Download the Yahoo Finance app for Apple or Android

Follow Yahoo Finance on Twitter, Facebook, Instagram, Flipboard, LinkedIn, and YouTube