The energy regulator has been asked to investigate allegations of price gouging by power companies.

Federal Energy Minister Josh Frydenberg says the Australian Energy Regulator will launch a probe into claims that energy companies have been overcharging customers by as much as $400 million a year.

Tax office figures from 2013 to 2016 reveal a discrepancy between the tax allowances the regulator previously set for network businesses and the amount they actually pay.

The companies have a cap on the amount they are allowed to charge for the maintenance of electricity poles and wires.

“It is totally unacceptable for consumers to be charged for corporate tax liabilities that are not actually incurred,” Mr Frydenberg said on Tuesday.

“The Turnbull Government wants to ensure consumers are paying no more for their energy than they have to.”

The regulator’s final report should be handed to COAG energy ministers by December.