HARD-UP households are warned that they could face a penalty if they make a common mistake.
Additional charges could be imposed on any household that does not pay its energy bill on time.
Some suppliers are now charging up to £25 to bill payers who miss a payment.
It comes as the cost of gas and electricity continues to soar amid the cost of living crisis.
ScottishPower introduced the surcharge earlier this year – customers being charged up to £20 if their bill is not paid after 28 days.
A number of other major energy companies also charge customers who miss a payment.
EDF Energy’s charge is £10 for customers with an outstanding balance of £50 or more that remains unpaid 28 days after the invoice date.
But the company said financially vulnerable customers and people with certain mental and physical disabilities are exempt from late payments.
E.ON Energy also charges £10 for late payment.
Energy giant British Gas is charging customers £13 if their payment is not made within 28 days of the invoice.
If the invoice remains unpaid after 36 days, customers will also be charged an additional £7.
Outfox the Market said it charged £25 for any missed or late payments.
Octopus, Bulb and M&S Energy all state in their terms and conditions that they charge £15 for the first missed payment, and £20 for each missed payment thereafter.
But an Octopus spokesperson said the company never charged customers fees or interest if they failed to pay on time.
Octopus said: “Instead of charging customers, we use different ways to engage and help customers who miss payments, and work with them to set up payment plans or payment holidays that work for them. allow them to pay their bills on their terms.”
Good Energy charges customers 3% interest on unpaid invoices after 28 days, in accordance with its terms and conditions.
Which energy companies do not charge late fees?
A number of energy providers do not impose formal charges on customers who make late payments.
Shell Energy does not bill late paying customers due to missed payment.
But if you pay your bill by direct debit and cancel the payment, you will be charged a £5 administration fee.
Utilita Energy also does not charge late payment fees.
So Energy said it ‘rarely imposes’ its £20 missed payment charge and has not charged it since the cost of living crisis began.
A spokesperson for the energy company said: “So Energy always seeks to engage with the customer to help them manage their payments before applying any charges.”
Energy regulator Ofgem said suppliers “must consider a customer’s circumstances and ability to pay” and will approach suppliers who fail to do so.
A spokesperson for Ofgem said: “All late bill payment charges must be clearly stipulated and explained by suppliers in their contracts with customers.
“Contracts can be changed by suppliers, but they must give sufficient notice and proper explanation.
“Any communication regarding unpaid or overdue invoices must be reasonably and fairly made.”
Consumer expert Martyn James said it was “unacceptable” for energy companies to charge late payment fees.
He said: “I would like all energy companies to commit not to charge these fees, pass debts on to collectors or cut people off for at least a year while the energy crisis continues.”
How to avoid late fees
If you are having trouble paying your gas and electricity bills, you should contact your supplier to discuss ways to pay what you owe them.
If you know you’re going to miss a payment, let your provider know and ask if they can waive the fee.
Citizens Advice says your provider should help you find a solution and help you find a deal that works for both of you.
Debt expert Andy Shaw of the charity Stepchange previously told The Sun that talking to them could mean you get the right support.
“All energy companies have an obligation to treat customers who are financially distressed or vulnerable for any other reason, such as health or age, fairly,” he said.
The exact help your provider can offer will depend on your situation and can range from grants and vouchers to repayment plans (see more below).
Here are all the ways you could get help from your provider – from prepayment vouchers to cash grants.
If you’re worried about paying bills, falling behind, or getting into debt, there are plenty of organizations where you can seek free advice, including: