British Gas is to take on the 176,000 customers of Together Energy, which ceased trading last week.
A British Gas statement said: "In line with the regulatory framework, it has been agreed with Ofgem that relevant costs, including the costs of buying energy incurred by British Gas that it is not able to recover as a result of taking on the customers, will be recoverable through the established industry levy in a timely manner.
"In the coming days, we will be in touch with Together Energy customers about the process of moving over."
