Simple rules overseen by the regulator prevent energy companies from billing customers for energy used more than 12 months ago, but they aren’t always adhered to. often helps exasperated energy customers resolve back-billing disputes. complaining that his direct debit bills from his energy supplier Eon were inaccurate. The Energy Security and Net Zero Committee, the government department that evaluates energy policies, looked into the practice of back-billing by energy companies earlier this year. It found that back-billing issues aren’t systemic but still affect thousands of energy customers and need to be addressed.