The January sales are not just for clearance jumpers and discounted air fryers. The UK's SIM only market traditionally gets very competitive at the start of each year as networks scramble to win new customers after Christmas - and 2026 is no exception. We have trawled the current crop of offers and picked out the strongest 5G SIM only plans available for under £10 a month.
Our top picks
- Smarty 100GB 5G: £7 per month, one-month rolling. Uses the Three network.
- iD Mobile Unlimited 5G: £9 per month, 12-month contract. First-ever sub-£10 unlimited plan.
- Voxi 50GB Endless Social: £8 per month, monthly rolling, unlimited social media.
- Lebara 30GB: £4 per month for three months, then £8. 12-month term.
- Lycamobile 60GB: £6 per month, 30-day rolling, free Lyca-to-Lyca calls.
Which one should you pick?
For most people, iD Mobile's unlimited 5G at £9 per month is the headline deal. It is the first time we have ever seen a UK-based network offer truly unlimited 5G data for less than £10 a month. The catch is the 12-month minimum term and the annual CPI + 3.9% price rise, but even factoring those in, it is excellent value.
If you prefer flexibility, Smarty remains the king of monthly rolling plans. There is no minimum contract, no mid-contract price hike (Smarty has pledged to never do this), and the network quality is identical to Three since Smarty is a Three MVNO.
Things to watch out for
- Most "from £4" deals are introductory offers - the price doubles or triples after three or six months
- Not all SIMs are 5G ready - check before you buy
- eSIM availability still varies between networks; iD, Vodafone and EE are fine, Smarty only launched eSIM support in late 2025
- Make sure you cancel your old contract in time if you are switching
How to switch
Text PAC to 65075 from your current phone to get your porting code. It is free, takes seconds and lets you keep your number when you move. All UK networks are legally required to port your number within one working day.