has shared a cash-saving tip for anyone who uses a mobile phone which could save hundreds of pounds per year.
The money saving expert assessed the most common bills facing households and looked for where costs can easily be cut, despite soaring energy prices.
Britain’s rate of inflation has rocketed to its highest level in almost 30 years as the cost-of-living crisis continues, with the Office for National Statistics (ONS) revealing that the Consumer Prices Index (CPI) jumped from 5.1% in November to 5.4% in December - the highest level since March 1992.
Food and non-alcoholic drink prices, coupled with rising costs for restaurants, hotels, furniture, household goods, clothing and footwear have all contributed to rising inflation, the ONS said.
Household finances are also being squeezed due to rising gas and electricity tariffs, and supply chain problems are pushing up costs across the economy.
The Bank of England has now forecast inflation to hit 6% in April.
While household spending will increase dramatically in April when energy bill caps go up by 50%, Mr Lewis said mobile phone bills are one regular expenditure that can easily be reduced.
How to reduce your mobile phone bill
On ITV's Martin Lewis Money Show Live, the finance expert surveyed Twitter and found 30% of respondents were paying more than £30 per month for their mobile phone.
However, Mr Lewis said the price of the average 4GB phone deal has halved over the past five years and urged people to check their contract to see if they are overpaying.
He said: “If you haven’t sorted out or changed your mobile phone deal, you are likely paying way too much.
“My big question would be, ‘are you paying over £10 a month?’ If so, why?
“If part of your bill is repaying a handset, fair enough. If it's because you roam a lot, then fair enough.
“Maybe if you’ve got poor credit and you have to be on pre-pay, but that shouldn’t be too much more expensive.
“The solution here is about switching your SIM card.
“Most deals these days are unlimited minutes and texts, so this is all about data. Nowadays the average use is 4GB a month - obviously if you stream a lot it will be a lot more.
“But you could get that seriously cheap.”
Mr Lewis said switching SIM cards could bring down the price of monthly mobile phone bills significantly and showed examples of cheap deals on offer.
This included a deal starting from just £6 per month for a 10GB deal with Lebara.
The money saving also addressed concerns that switching to a different network may affect a mobile phone signal, saying users should not be worried about a drop in service.
He explained: “There are only actually four networks - O2, EE, Vodafone and Three. Every other provider is piggybacking off their signal.
“Labara is using Vodafone, Plusnet is using EE. So if you want to cut your costs, you can keep the same signal but by changing to a different virtual network.
“The only thing I’d watch for is if you like WiFi calling or 5G or tethering it may not have it, so check before you sign up.”
Mr Lewis added that anyone who wants to switch their SIM card can keep their current mobile number by texting PAC for free to 65075.
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