Martin Lewis has urged all Brits who have an electricity meter to do a reading before the October price cap changes again.
It comes as new Prime Minister Liz Truss announced that energy bills will be capped for two years at £2,500 as an attempt to address the cost of living crisis.
In April, the Money Saving Expert founder recommended that everyone take a manual meter reading before the price hike.
This was recommended so that your energy supplier would know exactly how much energy you used before the new rates came in to prevent you from being overcharged.
It is being recommended to do this again on September 30, ahead of the new price cap coming into force on October 1.
Speaking on his ITV show, Mr Lewis said: "That way you draw a line in the sand that says to your energy firm, I've only used this amount at the cheaper rate."
To send a meter reading, record the first five numbers shown from left to right to your energy supplier. You can do this over the phone, online or through an app.
Digital meters will show five numbers in black and white, followed by one or more red numbers. The red numbers can be ignored.
Under the "Energy Price Guarantee" - also referred to as the October Price Freeze - which starts from October 1, a typical household will pay an average of £2,500 a year on their energy bills, frozen until 2024.
Some households may pay less than this, while others will pay more.
Ms Truss' interview came as the energy price cap was due to rocket to £3,549 from October 1 and even higher in 2023.
With existing government support of £400 per consumer, the average bill is now expected to be around £2,100.
Mr Lewis has also explained why some people could be hit with bills that exceed the average £2,500.
He said: "That £2,500 is an illustration of what the price cap would be for someone on typical use.
“What's actually capped is the standing charge, the amount you pay per day, and the unit rate, which is the amount you pay for each unit of electricity and gas you use.
"If you use more, then you pay more. If you use less then you pay less. So the idea your bill can't go up to £5,000 is nonsense. If you use a lot and that would be a lot then it could go up to £5,000."
