The UK Government has warned energy-supply firms not to hike direct debit payments for customers who are making "huge efforts" to cut usage.
The BBC says the business secretary has written to suppliers asking them to ensure bills reflect what homes are actually using, and do not over-estimate charges.
Grant Shapps said he was concerned by reports that bills were rising despite people cutting back on energy use. Regulator Ofgem has been asked to look at making billing "more responsive".
Ofgem said it had already called on firms to address the issue, but would be prepared to take further action if necessary.
Direct debit is the lowest cost method of paying energy bills, but can lead to overcharging, because suppliers calculate bills according to a customer's previous consumption and spread charges for higher winter use over the year.
Energy prices have been rising, due in part to sanctions imposed against Russia, a major oil and gas producer, following its invasion of Ukraine.
Ofgem plans
- Meanwhile, Ofgem has announced plans to make the energy-supply sector more resilient to market shocks, but has come in for criticism from one large player.
The watchdog is proposing to drop a plan to ring-fence customers' credit balances - which build up when direct debits are higher than energy used.
Instead, Ofgem said it would monitor closely firms' use of these balances.
British Gas owner Centrica accused Ofgem of an "abdication of responsibility".
A raft of energy suppliers have collapsed since the start of last year after being unable to cope with soaring energy prices. The UK Government is facing a bill of about £6.5billion for the collapse of supplier Bulb alone.
Ofgem is proposing a range of reforms, including making sure companies have sufficient financial strength to deal with future energy shocks. It said it will also require suppliers to ring-fence money they need to buy renewable energy.
No ring-fencing of credit balances
However, the regulator said it would not require ring-fencing of customers' credit balances.
Instead, it said it would just monitor companies' use of customers' credit balances more closely to stamp out misuse by firms. When a firm goes bust, this money is protected for customers - but the cost is usually shared among surviving suppliers.
This proposal not to ring-fence was criticised by Centrica chief executive Chris O'Shea.
"When customers pay up front for their energy, they are trusting their supplier to look after their hard-earned money," he told the BBC.
"They would be appalled to learn their money was being used to fund day-to-day business activities, but that's exactly what's happening in some companies - and it undermines confidence in the market."
He added that "if and when a large supplier fails, the recklessness of the decision not to address this issue will be clear for all to see".
The regulator said it was seeking responses from the industry and would publish the final reforms in the spring.