Octopus Energy said it would prematurely repay the £3 billion in state support it received for its acquisition of the collapsed energy supplier Bulb.
Set to be paid by September, the move from the energy firm will provide an early windfall for the next UK government.
Octopus became the largest electricity supplier in the UK following its state-backed takeover of Bulb, increasing its customer base to 6.9 million.
In November 2021, Bulb it was placed into special administration, with Octopus purchasing it in October 2022, helped by government funding.
The initial bailout cost, estimated to be as high as £6 billion, has been significantly reduced due to falling energy prices. The final bill is now projected at £3.02 billion.
Greg Jackson, chief executive of Octopus, said: "This outcome is a great result for taxpayers. Octopus worked hard in the darkest depths of the energy crisis to create a fair deal, meaning that although Bulb went bust with billions of liabilities, it has cost the government almost nothing."