Last updated: Monday 19 October 2026 (Europe/London).
Next update: when Three or Smarty change their SIM only prices, or before the April 2027 price rise.
By: Switch Editorial Team, Switch Squid Ltd
As of 19 October 2026, Three’s customer-only SIM deals start at £8 a month for 8GB and £13 a month for unlimited data on a 24-month Lite plan, but both rise every April, by £1.90 and £2.30 a month respectively. Smarty, which is run by the same company and uses Three’s network, charges £8 a month for 16GB on a one-month plan with no annual price rises. Three also lists Value and Complete unlimited plans for existing customers at £16 and £19. This SwitchSquid guide sets out what Three charges existing customers, what it must tell you before your contract finishes, how to ask for a better price, and when Smarty is the cheaper home for your number. We may earn a commission if you buy through links on this page; it doesn’t change the price you pay.
Sources: Three — offers for existing customers, Three — changes to your monthly charge, Three — SIM only plans, Smarty — 16GB plan, Smarty — 100GB plan and Ofcom — in or out of contract (all checked on 19 October 2026).
Smarty 16GB — £8 a month on Three’s network
16GB of data with unlimited UK calls and texts for £8 a month on a one-month plan when we checked on 19 October 2026
No annual price rises and no credit check, using Three’s network
Main limitation: 16GB suits light to moderate users, so heavy streamers may need a bigger plan
What Three charges existing customers in October 2026
Three now writes its yearly rises in pounds and pence instead of as a percentage. For customers who joined or upgraded from 19 April 2026, its network terms say the monthly charge goes up every 1 April by a fixed amount tied to your data allowance: £1.80 for plans of 4GB or less, £1.90 for plans from 5GB to 99GB, and £2.30 for 100GB or more, including unlimited. Home broadband plans go up by £3.50.
Older customers have been moved onto the same style of rise. Three’s support page says customers who joined or upgraded between 29 May 2015 and 7 September 2024, and who were outside their minimum term on 31 March 2026, saw fixed pounds-and-pence increases from 1 April 2026. Its own example shows a £30 unlimited SIM only plan moving to £32.30.
Because the rise is a flat amount, it bites hardest on cheap plans. On an £8 plan, £1.90 adds almost a quarter to the bill. Out-of-bundle charges and daily roaming charges, where they apply, rise each April by January’s Consumer Price Index plus 3.9%.
One more detail matters when you compare prices. Three says its monthly charges include a £5 discount for paying by a recurring method such as Direct Debit, so the headline price assumes you pay that way.
Three’s customer-only SIM deals right now
Three runs a page of offers that are only for people who already have an account. When we checked on 19 October 2026, it listed these 24-month SIM only plans:
Unlimited data, Lite plan: £13 a month (shown as down from £20), rising to £15.30 from 1 April 2027 and £17.60 from 1 April 2028.
Unlimited data, Value plan: £16 a month (shown as down from £22).
Unlimited data, Complete plan: £19 a month (shown as down from £39), including roaming in 49 Go Roam in Europe destinations.
8GB, Lite plan: £8 a month, rising to £9.90 from 1 April 2027 and £11.80 from 1 April 2028.
Lite plans are limited to speeds of up to 100Mbps. That is plenty for streaming and video calls on a phone, but it is a cap you won’t find on Smarty, which says its plans have no speed restrictions. Picking one of Three’s offers takes you to your My3 account, where you log in and the discounted price shows in the basket.
What Three must tell you before your contract finishes
Ofcom requires every mobile provider to send an end-of-contract notification by text, email or letter between 10 and 40 days before your minimum term is up. It must show the date your contract finishes, what you pay now, what you will pay afterwards, and the provider’s best deals, including any offered only to new customers. If you are already out of contract, Three has to remind you of its best deals once a year.
Keep that message. If it lists a new-customer price that beats your current bill, you have a written figure to quote when you ask Three for a better deal.
If you pay off a phone through a separate device plan, check that agreement too. The airtime and the handset can run on different terms, and ending one does not always end the other.
How to get a better price from Three
Start in the My3 app or website. Look at the upgrade options offered to your number and compare them with the customer-only page above. If the price in your account is higher than the one on Three’s offers page, call Three on 333 from your Three phone and ask them to match it.
Have three numbers ready: what you pay now, how much data you actually use each month (it’s in My3), and the cheapest plan you have seen elsewhere. If you use well under 16GB, say so. A plan you can move to without a contract gives you a strong position, because you are not bluffing about leaving.
Before you agree to anything, ask how long the new minimum term is, what the price will be after each April rise, and whether it is a Lite, Value or Complete plan. A 24-month plan at £13 will cost £15.30 from April 2027 and £17.60 from April 2028, so work out the full cost rather than looking at the first bill.
Why Smarty is the obvious alternative for Three customers
Smarty’s website says it is a trading name of Hutchison 3G UK Limited, the company behind Three. It uses Three’s network, so if your signal is good on Three at home and at work, it should be much the same on Smarty.
The difference is in the contract. Smarty sells one-month plans you can cancel or change at any time, with no credit check and, it says, no annual price rises. When we checked on 19 October 2026, its plans included 16GB for £8 a month, 100GB for £12, and unlimited data for £20. All include unlimited UK calls and texts, 5G where your phone supports it, Wi-Fi calling, and EU roaming with a 12GB fair use limit. You can choose a physical SIM or an eSIM.
Smarty’s 16GB plan costs the same as Three’s 8GB customer deal today but gives you twice the data, and it doesn’t step up to £9.90 next April. You can also tether or use your phone as a hotspot with all of your data while you’re in the UK. You can ask Squid AI, SwitchSquid’s AI deal assistant, to compare plans by the data you actually use before you decide.
Three vs Smarty: 24-month cost compared
Plan | Data | Price now | Price from April 2027 | Cost over 24 months* | Contract |
|---|---|---|---|---|---|
Three customer deal, Lite | 8GB | £8 a month | £9.90 a month (£11.80 from April 2028) | £241.40 | 24 months |
Three customer deal, Lite | Unlimited (up to 100Mbps) | £13 a month | £15.30 a month (£17.60 from April 2028) | £371.80 | 24 months |
Smarty | 16GB | £8 a month | No annual price rise | £192.00 | 1 month, rolling |
Smarty | 100GB | £12 a month | No annual price rise | £288.00 | 1 month, rolling |
Smarty | Unlimited | £20 a month | No annual price rise | £480.00 | 1 month, rolling |
*Assumes you start in November 2026 and pay 24 monthly bills, with Three’s rises applied from April 2027 and April 2028. Smarty totals assume its price stays the same; rolling plans can change price, but Smarty would tell you first and you could leave. Three prices are from its customer-only page and assume payment by Direct Debit. All prices checked on 19 October 2026.
The table shows an honest split. If you use less than about 16GB, Smarty is cheaper and gives you more data. If you want truly unlimited data and don’t mind a 24-month contract capped at 100Mbps, Three’s £13 Lite deal for existing customers works out cheaper than Smarty’s £20 unlimited plan, even after two April rises. Somewhere in between, Smarty’s 100GB plan at £12 suits most heavy users without tying you in.
Smarty 100GB — £12 a month for heavier users
100GB of data with unlimited UK calls and texts for £12 a month on a one-month plan when we checked on 19 October 2026
EU roaming included, up to a 12GB fair use limit
One-month plan, so you can change or leave at the end of any month
How to move from Three to Smarty and keep your number
Check your end date. Leaving during a minimum term can mean early termination charges, so look in My3 first.
Get your PAC code. Text PAC to 65075 from your Three phone. It’s free, and you should be told about any charges for leaving early when the code arrives. If you want a new number instead, text STAC to 75075.
Order the Smarty plan. Choose a SIM or eSIM. When it’s active, give Smarty your PAC code and number.
Let the switch happen. Ofcom says your number should normally move within one working day once your new provider has the code, and providers can’t charge for notice periods that run beyond the switch date.
Keep paying any device plan. If you’re still paying off a phone with Three, carry on paying it or clear it.
Sources: Ofcom — switching mobile (checked on 19 October 2026). For more on codes and timings, read our guide to getting a PAC code. If you’d rather compare more fixed-price networks, see our guide to SIM only deals with no price rises, and our Three SIM only deals page lists plans for new customers.
Should you stay with Three?
Staying can make sense if you want unlimited data and are happy with a two-year commitment. The £13 Lite deal is good value on paper, and Three’s Complete plan adds roaming in 49 European destinations, which helps if you travel often. Three+ rewards are included on its plans as well.
Moving makes more sense if your usage is modest or you value flexibility. A one-month plan means you never have to accept an April rise mid-contract, and you can drop to a cheaper allowance in a quiet month. Our existing-customer guides for EE and O2 follow the same approach if someone else in your household is on another network.
Fit summary
Good fit for Smarty 16GB or 100GB: Three customers out of contract who want the same network, no credit check and no annual rises.
Good fit for re-contracting with Three: heavy users who want unlimited data at £13 and can live with a 24-month term and a 100Mbps cap.
Think twice: anyone with time left on a Three minimum term or a device plan, where leaving early may cost more than you save.
Important conditions
Three’s customer deals are for existing account holders and are taken through My3; the price you see there can differ from the offers page.
Three’s quoted prices include a £5 monthly discount for paying by Direct Debit or another recurring method.
Three rises are fixed each April: £1.80, £1.90 or £2.30 a month depending on your data, and £3.50 for home broadband.
Smarty plans run month to month. Smarty says there are no annual price rises, but prices on rolling plans can change with notice.
Smarty uses Three’s network, so check coverage for your postcode before you move.
Final decision card
Out of contract with Three and using under 16GB? Smarty’s 16GB plan is £8 a month with no contract and no annual rise.
Need lots of data but no lock-in? Smarty’s 100GB plan is £12 a month.
Want unlimited data for less and happy to commit? Ask Three for its £13 Lite customer deal in My3.
Keep Three’s coverage for £8 a month
Smarty 16GB, unlimited UK calls and texts, £8 a month
Keep your number with a free PAC code: text PAC to 65075
Check coverage for your postcode before you order
FAQ
Can existing Three customers get new-customer SIM only deals?
Three runs a separate page of customer-only SIM deals, and when we checked on 19 October 2026 it started at £8 a month for 8GB. Your end-of-contract notification must also list Three’s best deals, including new-customer prices. If the price in My3 is higher, call 333 and ask Three to match it.
How much will my Three bill go up in April 2027?
Three says plans of 4GB or less rise by £1.80 a month, plans from 5GB to 99GB by £1.90, and plans of 100GB or more, including unlimited, by £2.30. Home broadband rises by £3.50 a month. Device plan repayments and add-ons don’t get the yearly rise.
Does Smarty use the Three network?
Yes. Smarty is a trading name of Hutchison 3G UK Limited, the company behind Three, and runs on Three’s network. Your coverage should be much the same as it is on Three.
Does Smarty put prices up every April?
Smarty says its one-month plans have no annual price rises. Because the plans roll month to month, a price could still change, but you would be told first and could leave or change plan without a penalty.
What is a Three Lite plan?
Lite is Three’s entry tier, and its plans are limited to speeds of up to 100Mbps. Value and Complete plans cost more and add extras, such as roaming in 49 European destinations on Complete. For most phone use, 100Mbps is enough, but it is slower than Three’s top tiers.
How do I keep my number when I leave Three?
Text PAC to 65075 from your Three phone to get a free PAC code. Give it to your new provider, and Ofcom says the number should normally move within one working day. You don’t need to call Three separately to cancel.
