Billionaire Elon Musk has said his time leading President Donald Trump's cost-cutting task force is coming "to an end".

In a post on his social media platform X, Musk thanked Trump for the opportunity to help run the Department of Government Efficiency - known as Doge.

He was designated as a "special government employee" - allowing him to work a federal job for 130 days each year. Measured from Trump's inauguration on 20 January, he would hit that limit towards the end of May.

Musk's exit comes after he criticised Trump's "big, beautiful" budget bill - the legislative centrepiece of the president's agenda.

"As my scheduled time as a Special Government Employee comes to an end, I would like to thank President @realDonaldTrump for the opportunity to reduce wasteful spending," Musk wrote on X.

"The @DOGE mission will only strengthen over time as it becomes a way of life throughout the government."

The BBC understands that the White House will begin "offboarding" Musk as a special government employee on Wednesday night.

Musk's exit comes after he said he was "disappointed" with Trump's budget, which proposes multi-trillion dollar tax breaks and a boost to defence spending.

The SpaceX and Tesla boss said in an interview with BBC's US partner CBS that the bill would increase the federal deficit, adding that he thought it "undermines the work" being done at Doge.

The Republican megadonor's departure caps a tumultuous foray into politics that transformed him into one of Trump's closest advisers and saw plunging profits at his electric car company.

Tesla recently warned investors that the financial pain could continue, declining to offer a growth forecast while saying "changing political sentiment" could meaningfully hurt demand for the vehicles.

Musk told investors on an earnings call last month that the time he allocates to Doge "will drop significantly" and that he would be "allocating far more of my time to Tesla".