One in five business energy bills contain mistakes, according to utility advisor Inenco.

Incorrect rates, meter reading errors and other common mistakes are costing businesses up to £500 million, the firm said in its “Uncovering the Missing Millions” report.

The company analysed thousands of energy bills in order to compile the research.

Mistakes when calculating the Climate Change Levy accounted for 10% of errors.

Retailers and manufactures among worst hit

Retail and leisure businesses were the subjects of 42% of the errors.

Manufacturers accounted for a further 13% and the public sector clocked up 22%.

Inenco said: “Businesses can recover incorrect charges for the past six years.”

Meanwhile, Ofgem has unveiled proposals to stop energy suppliers from back-billing domestic customers for energy used more than 12 months ago.

> Download the report