Last updated: Sunday 1 November 2026
The best SIM only deals for kids are short, capped plans that a parent controls. As listed on 1 November 2026, SMARTY’s 18GB plan costs £6 a month on a one-month contract with no credit check, iD Mobile’s 25GB rolling plan costs £7 a month with bill capping, and giffgaff’s 15GB pay as you go plan costs £10 with no contract at all. Each one lets you cancel or change the plan every month, so a child’s first phone does not tie you into 24 months of payments. Ofcom’s 2026 research shows phone ownership jumps from 56% of 10-year-olds to 83% of 11-year-olds, so the start of secondary school is when most families make this choice. This SwitchSquid guide compares the plans, explains who holds the account and covers the controls worth switching on. If you buy through the buttons on this page, we may earn a commission; it does not change the price you pay.
Sources: Ofcom children’s media research, May 2026, O2 age-restricted content, Vodafone content control and the SMARTY, iD Mobile and giffgaff plan pages, all as listed on 1 November 2026.
SMARTY 18GB for £6 a month, one-month plan
- 18GB for £6 a month with unlimited UK calls and texts, as listed on 1 November 2026
- No credit check, no annual price rises and cancel or change anytime
- Main limitation: runs on Three, so check coverage at home and school first
SIM only deals for kids: the short answer
Cheapest: SMARTY 18GB for £6 a month, one-month plan, no credit check and no annual price rises.
Best spending control: iD Mobile 25GB for £7 a month on a 30-day rolling plan, with bill capping and data rollover.
No contract at all: giffgaff 15GB for £10 on pay as you go, which lasts a month and then waits for you to choose the next plan.
Avoid for a first phone: long contracts with a handset, unless you are sure the phone and the allowance will suit your child for two years.
Kids’ SIM plans compared
All prices are as listed on 1 November 2026 on each provider’s own plan page. The 12-month cost assumes you keep the same plan for a year and the price stays the same.
Plan | Data | Monthly price | Commitment | Network | Spending control | 12-month cost |
|---|---|---|---|---|---|---|
SMARTY 18GB | 18GB | £6 | One month, cancel anytime | Three | Price capped per month, no credit check | £72 |
iD Mobile 25GB | 25GB | £7 | 30-day rolling | Three | Bill capping, no annual price rises | £84 |
giffgaff 15GB pay as you go | 15GB | £10 | No contract, one month at a time | O2 | Nothing renews unless you choose a new plan | £120 |
giffgaff 20GB monthly rolling | 20GB | £10 | Monthly rolling, no contract | O2 | Renews each month until you change it | £120 |
All four include unlimited UK calls and texts. If your child mostly uses Wi-Fi at home and at school, 15GB to 25GB a month is plenty for messaging, maps and some video. Our SIM only deals under £10 guide lists more low-cost plans.
Can a child have their own SIM only contract?
Not in their own name. O2 says you need to be over 18 to get a pay monthly contract, and the same applies across UK networks, because a contract is a credit agreement. In practice, a parent or guardian takes out the plan, pays for it and holds the account, and the SIM goes in the child’s phone.
That has two advantages. You can see the bill and change the plan from your own app, and you can cancel a one-month or rolling plan if the phone is lost or the arrangement is not working. With pay as you go, there is no contract at all, so the account holder simply buys the next plan each month.
If you need a new number, the SIM comes with one. If your child already has a number on an old phone, text PAC to 65075 from that phone to get a code and keep it. Our guide to getting a PAC code explains the steps.
SMARTY 18GB at £6: cheapest and simplest
SMARTY runs on the Three network and sells one-month plans only, so there is no long contract to unwind. As listed on 1 November 2026, its plan page shows 18GB for £6 a month, with unlimited UK calls and texts, 5G where your phone supports it and no speed limits. SMARTY says there is no credit check and no annual price rises, and you can choose a physical SIM or an eSIM.
The monthly price is capped, so the bill cannot creep up during the month. SMARTY also includes EU roaming with a 12GB fair use limit, which helps on school trips and family holidays in Europe. The main thing to check is coverage where your child spends time: SMARTY quotes 99.5% outdoor coverage, but indoor signal varies by building. Our SMARTY review covers the app and support.
iD Mobile 25GB at £7: best for controlling spending
iD Mobile also uses the Three network. Its 25GB plan, as listed on 1 November 2026, costs £7 a month on a 30-day rolling contract, with unlimited minutes and texts and no annual price rises. The checkout page lists bill capping, which lets the account holder set a limit so out-of-allowance charges cannot push the bill past it.
iD also rolls unused data into the next month once, which suits children whose use goes up and down with school holidays. It is a pay monthly plan, so the parent will go through iD’s checks when ordering. Our iD Mobile review has more on its network and perks.
iD Mobile 25GB for £7 a month, 30-day rolling
- 25GB for £7 a month on a 30-day rolling plan, as listed on 1 November 2026
- Bill capping and no annual price rises, with unused data rolled over once
- Main limitation: a pay monthly plan, so the account holder goes through iD’s checks
giffgaff pay as you go: no contract and no surprises
giffgaff runs on the O2 network. Its 15GB pay as you go plan, as listed on 1 November 2026, costs £10 and lasts a single month. When it finishes, nothing renews until you choose the next plan online, so there is no monthly bill to run up and nothing to cancel if your child stops using the phone.
The plan includes unlimited UK calls and texts, 5G at no extra cost and EU roaming up to 5GB. If you would rather not log in each month, giffgaff’s 20GB monthly rolling plan at £10 renews automatically and can be changed or stopped at any time. giffgaff costs more than SMARTY or iD for the data, so it suits families who value having no contract over the lowest price.
Parental controls to switch on
A SIM only plan does not set up a phone for a child by itself. These are the controls worth turning on in the first week:
Network content filter: UK networks place adult-rated content behind age checks under the mobile operators’ code of practice. O2 says it blocks 18+ content classified by the BBFC unless you prove your age. Ask your provider how its filter works on your plan.
Wi-Fi filter too: Vodafone points out that a mobile content bar only works on the mobile network, not on Wi-Fi. Turn on your home broadband’s family filter as well.
Phone settings: Screen Time on iPhone and Family Link on Android let you set app limits, approve downloads and see location.
Spending: block premium-rate services and in-app purchases, and use bill capping where it is offered.
Location sharing: agree with your child which apps can see where they are, and check it together.
Our guides to avoiding mobile phone scams and blocking unwanted calls are worth reading together with your child.
How much data does a child need?
Ofcom’s 2026 report found that 8 to 14-year-olds spend an average of one day a week online, rising to two days a week for 15 to 17-year-olds, though much of that is on home Wi-Fi. As a rough guide for mobile data away from Wi-Fi:
Ages 10 to 12, messaging and maps: 5GB to 15GB a month.
Ages 13 to 15, plus social media and music: 15GB to 25GB.
Ages 16 to 17, plus video and hotspot use: 25GB or more.
Starting on a one-month or rolling plan means you can move up or down after a few weeks once you see real use in the app. For older teenagers, our student SIM only deals guide covers bigger allowances, and family SIM sharing explains plans that put several lines on one bill.
Fit summary
Choose SMARTY 18GB if: you want the lowest monthly price, no credit check and a plan you can stop at any time.
Choose iD Mobile 25GB if: you want bill capping and data rollover, and do not mind a pay monthly check.
Choose giffgaff 15GB if: you want no contract at all and are happy to buy each month’s plan yourself.
Think again about a handset contract if: it is a first phone and you are not sure it will last two years.
Want help choosing? Ask Squid AI, SwitchSquid’s assistant, which plan fits your child’s use and your budget.
Important conditions
Prices are as listed on 1 November 2026 and can change. Check the plan at checkout.
The account holder must be 18 or over for pay monthly plans and is responsible for the bill.
Network content filters cover mobile data, not Wi-Fi. Set up filters on your broadband and the phone itself too.
Coverage varies by area and building. Check the network’s coverage map for home and school postcodes.
Phones must be unlocked to use a SIM from a different network.
Final decision card
For most families, SMARTY 18GB at £6 a month is the simplest first SIM for a child, as listed on 1 November 2026, with no credit check and no long contract. iD Mobile 25GB at £7 adds bill capping, and giffgaff 15GB at £10 avoids a contract altogether. Start short, watch the data use for a month, then adjust.
giffgaff 15GB pay as you go for £10, no contract
- 15GB for £10 for one month on pay as you go, as listed on 1 November 2026
- No contract: nothing renews until you choose the next plan, with EU roaming up to 5GB
- Main limitation: dearer for the data than SMARTY or iD
FAQ
What is the best SIM only deal for a child?
SMARTY 18GB at £6 a month is the cheapest of the plans compared here, as listed on 1 November 2026. iD Mobile 25GB at £7 adds bill capping. giffgaff 15GB at £10 has no contract at all.
Can a 12-year-old have a SIM only contract?
Not in their own name, because pay monthly contracts need an account holder aged 18 or over. A parent or guardian takes out the plan and puts the SIM in the child’s phone. Pay as you go needs no contract.
What age do most children get a phone in the UK?
Ofcom’s 2026 research found that 56% of 10-year-olds own a mobile phone, rising to 83% of 11-year-olds. That makes the move to secondary school the most common point for a first phone.
Do SIM only plans have parental controls?
Most UK networks put adult-rated content behind age checks on mobile data. These filters do not cover Wi-Fi, so also use your broadband filter and the phone’s own controls, such as Screen Time or Family Link.
How do I stop my child running up a big phone bill?
Choose a plan with a capped price or bill capping, such as SMARTY or iD Mobile, or use pay as you go. Block premium-rate numbers and in-app purchases on the phone too.
How much data does a child need each month?
Most 10 to 12-year-olds manage with 5GB to 15GB if they use Wi-Fi at home and school. Teenagers who watch video or use social media on the move may need 25GB or more. A rolling plan lets you change once you see real use.
Can my child keep their old number?
Yes. Text PAC to 65075 from the old phone to get a code, then give it to the new provider when you order or activate the SIM. The number usually moves within one working day.
