Martin Lewis has warned energy customers that ditching direct debits means their bills will go up by 7% a year on average.
Energy bills could hit an eye-watering £3,300 on average from October as the cost of living crisis continues to grip families.
Many customers are tempted to stop paying their bills by direct debit to help with budgeting.
The idea is that if an unexpectedly large energy bill direct debit goes out then it could wreak havoc on household finances.
Choosing to pay when you get a bill may look safer as a result.
But speaking on a Facebook Live broadcast today, the Money Saving Expert founder said doing this means you pay more for your energy overall.
The problem will be worsened once energy bills rise again in October.
Lewis said: "To have a bill rather than direct debit you will pay seven per cent more.
"That doesn't sound too much, does it? But once you get into the October price cap you are talking a couple of hundred quid more a year to have those bills.
"Direct debits affect your cash flow, but it is cheaper and you pay less overall, so it is a difficult decision."
Lewis also urged customers not to try to remove their own meters to save money, following a trend on social media.
He said: "Do not try to remove your own meter. It's dangerous, to start with."
He added that some people on social media believe you pay for having a meter - so no meter, no bill.
The finance expert said this was "crackers".
Earlier this month energy regulator Ofgem told a number of energy suppliers to take "immediate and urgent action" after a review found problems with how they charge customers.
Out of a total of 17 large suppliers in the market most had minor issues, but five were found to have "moderate or severe" weaknesses.
Ofgem is asking all energy firms that hiked 500,000 customers' direct debits by more than 100 per cent to review these bills.
Ofgem added: "Where appropriate, Ofgem also expects suppliers to adjust any miscalculations, including making repayments if needed, and consider whether a goodwill payment is warranted."
Energy firms have to review the accounts of all customers whose direct debits increased by 100% or more between February 1 and April 30, 2022.
The average energy bill rose by 62 per cent in this period for people paying by direct debit.
