Prepay for your energy? You could keep today's cheaper rates for a little longer – here's how

We've also contacted smaller suppliers to check it works with them and will update this when we hear back. In the meantime, you may want to check directly if you're not with one of the providers we've mentioned above. 

What's more, following reports that some MoneySavers were told this trick wouldn't work, we reached out to the firms above to check again that they wouldn't try to reclaim, backdate or otherwise bill for the extra, and so far British Gas, Bulb, EDF, Octopus, Ovo, SSE and Shell Energy have all reiterated that they wouldn't. 

What's more, Ofgem told us: "Customers on non-smart prepayment meters building up credit prior to an increase in their tariff under the price cap would not be regarded as ‘underpayment’, but simply a consequence of the non-smart prepayment topping up process. There is no mechanism under the price cap specifically for suppliers to reclaim money associated with customers building up credit in this way."

How exactly does it work and how much can I top up?

Generally when a price change happens, for those with older prepayment meters, the information about the new rates is sent to the terminals where you top up your key or card. This is transferred to the card when you top it up, then to your meter when you next plug it in.

That means you'll only start being charged the new rates once you top up after Friday 1 April. So you could potentially put as much credit on your meter as you can, and then use that for as long as possible – letting you use energy at the current rates and delaying having to pay the much higher rates under the cap from April.

Yet there is a limit on how much you can top up each time, and how much credit your meter can hold. We asked all the big names and they said that usually you can top up between £1 and £49 at a time, while the meter itself can typically hold up to £249 for electricity and up to £999+ for gas (depending on the meter). So to max the trick, you'd have to pay a few visits to the top-up shop.

Struggling to pay or repaying debt? What to do

Prepayment meters are often used to pay back debt that you may have accumulated in the past. If that's you, while there will still be some gain using this trick, be aware that most suppliers will take an additional amount on top of what you use yourself. And some, such as E.on Next, require you to top up weekly if you're repaying debt.

If you're having issues paying for your gas and electricity, our new Struggling with energy bills? guide details all the help available, including when to speak to your provider, what grants and help schemes you may be able to access, how to get free energy and debt advice and freebies and grants to improve your home's energy efficiency, and more.

It's also worth seeing if you can use less to cut bills – our energy saving tips help with the simpler stuff, such as turning your thermostat down and cutting shower time, while our Energy mythbusting guide looks at the less clear-cut questions, such as whether to leave the heating on low all day.