If you have a smartphone that you bought on contract and are slowly paying back with monthly installments, you might want to check your bills to see if you are overpaying.

Price comparison firm Uswitch says Brits are at risk of spending an estimated £1.77 billion combined per year on phones that they already own. This warning is based on Ofcom data that 19 percent of all handset customers are out of contract, which means they have already paid off the cost of their handset but are still paying the original contract price.

So for example, if you bought an iPhone or Android phone on a two-year contract, your total monthly payment is the spread cost of the handset plus your chosen mobile plan. After 24 months, the cost of your phone is paid off, but mobile operators and resellers can legally continue to charge you the full amount, resulting in what Uswitch refers to as ‘double paying’.

The firm says five million mobile users in the UK could be overpaying without realising and could save an average of £351 per year by moving to a SIM-only deal.

“This calculation is based on the price of the top-selling 24-month handset package in January 2023 (Apple iPhone 14 with 100GB data) against the cheapest equivalent SIM-only deal on the Uswitch site as of January 2025 (TalkMobile 100GB data £9.95 per month on average)”, Uswitch said.

“It’s important to remember that if your bundled phone contract includes a handset, you’re essentially ‘paying it off’ with your monthly phone bills,” said Ernest Doku, mobiles expert at Uswitch.

“Once your initial contract ends, you’ve contractually finished paying off the phone. However, this won’t be reflected in your monthly payments, and you’ll continue to pay the same amount as before, if not more.”

If you’re not sure if you are still paying off the cost of your phone you can check with your mobile provider or, Doku says, text INFO to 85075. This is a free way to check if you can leave your contract early without paying an exit fee, or to see if you have already paid it off. You’ll receive a reply by text message with the accurate information.

If you are out of contract, you can easily keep your mobile number and switch to a much cheaper SIM only plan. These plans are popular with people who own a phone outright and want to pay a cheaper monthly bill that, crucially, will not rise with some providers. For example, providers Giffgaff and Smarty offer mobile plans on a rolling monthly basis and never raise their prices, so you can leave at any time and won’t get bill shock.

“If you’re still in contract remember to set a reminder for when your contract ends. Even seemingly small costs can add up over time, so it’s crucial to review your contract and make changes as needed,” Doku said.

“If you do choose to switch providers, you can still keep your old mobile number. Just text “PAC” to 65075 for free and you will receive your PAC code. Once you receive the PAC code from this number, give it to your new provider and they will do the rest.”