Last updated: Tuesday 6 October 2026 (Europe/London).
Next update: when Mozillion changes Pay Monthly Plus prices, data tiers or terms.
By: Switch Editorial Team, Switch Squid Ltd
As of 6 October 2026, Mozillion Pay Monthly Plus gets you 310GB of data a month for £100 upfront followed by 23 monthly payments of £4. That is £192 over 24 months, or the equivalent of £8 a month. You get unlimited calls and texts, uncapped 5G and EU roaming in 41 destinations, and Mozillion says there is no credit check. The catch is the upfront payment: you pay roughly half the contract cost on day one. After that, the monthly bill is among the lowest you will find for a big data SIM in the UK.
If you would rather keep the upfront cost down, the same plan type comes in 10GB (£62.50 upfront + £2.50 a month), 30GB (£68.75 + £2.75) and 100GB (£81.25 + £3.25). For most people who stream, tether or work from their phone, though, the 310GB tier gives by far the most data for the money.
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Mozillion Pay Monthly Plus 310GB: £100 upfront, then £4 a month
- 310GB data a month, unlimited calls and texts, uncapped 5G
- 24 months: £100 upfront + 23 × £4 = £192 in total (£8 a month equivalent)
- The catch: about half the contract cost is paid at checkout
What is Mozillion Pay Monthly Plus?
Pay Monthly Plus is a hybrid between a traditional monthly SIM-only contract and a fully prepaid ("preloaded") SIM. Mozillion explains it like this: you pay 50% of the total plan cost upfront, along with your first month's payment, and the remaining balance is spread across the rest of the term. Plans run for 12 or 24 months. The deals in this guide are all 24-month terms.
Here is how that works on the 310GB plan:
- Total cost over 24 months: £192 (£8 × 24).
- Half the total: £96.
- First month's payment: £4.
- Upfront at checkout: £96 + £4 = £100.
- Then: 23 payments of £4 = £92.
- Grand total: £100 + £92 = £192.
The maths is identical across the range, so the headline "equivalent per month" figure is simply the 24-month total divided by 24. That makes Pay Monthly Plus easy to compare with other SIM deals. Look at the total you will pay over the contract, not just the monthly direct debit.
According to Mozillion, the benefits are the same as on its standard Pay Monthly SIMs. Paying part of the contract upfront is what brings the price down. The plans include:
- Unlimited UK minutes and texts
- Uncapped 4G and 5G speeds (no throttling)
- EU roaming in 41 destinations, including Spain, France, Portugal, Ireland, Greece and Italy
- Hotspot (tethering) and Wi-Fi calling
- Keeping your existing number via a PAC code
- No mid-contract price rises and no credit check
The full Pay Monthly Plus price ladder (24 months)
All prices below were checked on Mozillion's own plan pages on 6 October 2026. The "equivalent per month" column is the 24-month total divided by 24.
| Plan (24 months) | Upfront | Then 23 × monthly | Equivalent per month | 24-month total |
|---|---|---|---|---|
| Pay Monthly Plus 10GB | £62.50 | £2.50 | £5.00 | £120 |
| Pay Monthly Plus 30GB | £68.75 | £2.75 | £5.50 | £132 |
| Pay Monthly Plus 100GB | £81.25 | £3.25 | £6.50 | £156 |
| Pay Monthly Plus 310GB (best value) | £100.00 | £4.00 | £8.00 | £192 |
| For comparison: 150GB preloaded | £180.00 | £0 | £7.50 | £180 |
Two things stand out. First, the gap between plans is small once you look at the per-month equivalent. Moving from 10GB to 310GB costs £3 a month more on average, but gives you 31 times the data. Second, the 310GB plan costs only 50p a month more than Mozillion's own 150GB preloaded SIM (£180 paid once for 24 months), yet more than doubles the allowance. You also pay £80 less on day one, because the rest is spread across 23 monthly payments.
Best value in the table: 310GB for £192 over 24 months
- £100 today, then 23 monthly payments of £4
- More than double the 150GB preloaded allowance for about 50p a month more
- EU roaming in 41 destinations, no mid-contract price rises
Is 310GB for £8 a month the cheapest big data SIM in the UK in October 2026?
On a cost-per-gigabyte basis, it is very hard to beat. When we checked the market on 6 October 2026, most mainstream big data SIMs from the major networks and their sub-brands sat in the £10 to £20 a month range for 100GB to unlimited data. Many of those are rolling or 24-month contracts with no upfront payment, but the monthly bill is two to three times higher. Some also carry annual price rises during the contract.
Mozillion's 310GB Pay Monthly Plus plan works out at about 2.6p per gigabyte per month if you use the full allowance. That is far below the typical big-data SIM. The trade-offs are:
- The £100 upfront payment. If you cannot spare £100 today, a no-upfront monthly SIM may suit you better, even if it costs more over two years.
- The 24-month commitment. There is no one-month rolling version of Pay Monthly Plus. If you think you might switch networks, move abroad or upgrade to a phone contract within a year, think about whether a shorter deal fits better.
- It is not unlimited. 310GB is a huge allowance (roughly 10GB a day), but it does have a ceiling. Mozillion lists a separate Unlimited plan if you need one.
For most people, 310GB is effectively unlimited. Streaming HD video uses around 2 to 3GB an hour. You would need to stream for more than three hours every single day before you came close to the limit.
Who should choose the 310GB plan?
The 310GB tier makes most sense if one or more of these applies to you:
- You tether a laptop or tablet regularly. Hotspot is included, so you can work from a train, a campsite or a hotel where the Wi-Fi is poor.
- You use your phone as a home broadband backup. If your fixed line goes down, or you are waiting for a broadband installation, 310GB gives you real headroom.
- You stream a lot on mobile data. Football, box sets and music on the commute add up quickly on a 30GB plan.
- You want to stop thinking about data. At £8 a month equivalent, the step up from 100GB (£6.50) is only £1.50 a month.
If you only use your phone for messaging, maps and the odd video, the 10GB or 30GB plans will save you a little on the upfront cost. Our guide to the Mozillion 30GB Pay Monthly Plus SIM goes into that tier in more detail.
Mozillion Pay Monthly Plus vs Mozillion 150GB preloaded
Mozillion also sells a preloaded 150GB SIM: you pay £180 once and get 150GB a month for 24 months (about £7.50 a month equivalent). It is still a strong deal, and we cover it in our Mozillion 150GB SIM guide. Here is how the two compare:
- Data: 310GB on Pay Monthly Plus vs 150GB on preloaded.
- Total cost over 24 months: £192 vs £180, a £12 difference.
- Day-one payment: £100 vs £180, so Pay Monthly Plus is £80 easier on your bank balance at checkout.
- Ongoing payments: 23 × £4 on Pay Monthly Plus; nothing further on preloaded.
If you prefer to pay once and forget about it, the preloaded 150GB SIM is simpler. If you want more data and a smaller upfront payment, the 310GB Pay Monthly Plus plan is the better value. For 50p more a month you get more than twice the allowance.
What about EU roaming?
All Pay Monthly Plus plans include roaming in 41 destinations, including popular holiday spots such as Spain (including the Canary and Balearic Islands), France, Portugal, Greece, Italy, Ireland, Cyprus and Malta. Roaming covers local landline and mobile calls within the same country.
Roaming data is subject to a fair-use allowance that is smaller than your UK allowance. Mozillion lists up to 25GB for its larger data plans and lower amounts for smaller tiers (for example 2.5GB on 10GB and 7.5GB on 30GB). Check the plan details on Mozillion's site before you travel, especially if you plan to tether abroad. Calls from the UK to EU numbers are not the same as roaming and may not be included.
How to sign up and keep your number
- Check your phone is unlocked. Mozillion says all mobiles work on its network as long as they are unlocked. Phones bought new in the UK after December 2021 should already be unlocked. If yours is not, ask your current network.
- Get your PAC code if you want to keep your number. Text PAC to 65075 from your current phone, and you should receive it straight away.
- Choose your plan on Mozillion's site and pay the upfront amount at checkout.
- Give Mozillion your PAC code when prompted, or after your SIM arrives, so your number transfers.
- Insert the SIM when it arrives and your new plan will start.
Before you leave your current provider, check whether you are still in a minimum term. Leaving early can trigger early termination charges from your old network.
What happens at the end of the 24 months?
Mozillion says it will contact you at least a month before your plan ends. At that point you can take out another Pay Monthly Plus plan or move to any of its other SIM-only plans. You can also port your number to a different network. As with any SIM deal, it is worth comparing prices again near the end of your term rather than letting the plan roll on unchecked.
Things to check before you buy
- Upfront payment: make sure you are comfortable paying around half the contract value on day one.
- Contract length: the plans in this guide are 24 months. You are committing to the remaining 23 payments.
- Data rollover: Mozillion says unused data does not normally roll over from month to month.
- Roaming limits: check the fair-use roaming allowance for your tier before travelling.
- Coverage: use Mozillion's coverage checker for your home and work postcodes before you switch.
- Price changes: prices can change at any time. We last checked them on 6 October 2026. The price shown at checkout is the one that counts.
If you are a student looking for value, our student SIM-only deals guide compares Mozillion with other budget options, and our cheapest unlimited SIM-only guide covers truly unlimited plans if 310GB is still not enough.
Our verdict
For anyone who uses a lot of mobile data and can spare £100 at checkout, Mozillion Pay Monthly Plus 310GB is one of the best-value big data SIMs we have seen in October 2026. You get £192 over 24 months for 310GB a month, unlimited calls and texts, uncapped 5G, EU roaming and no mid-contract price rises. The 100GB, 30GB and 10GB tiers are there if you want a smaller upfront payment, but the jump to 310GB costs very little extra per month.
Check Mozillion Pay Monthly Plus 310GB on your phone
- Works with any unlocked phone; keep your number with a PAC code
- £100 upfront + 23 × £4 over 24 months (£192 total)
- Prices checked 6 October 2026 — the checkout price is the one that counts
Frequently asked questions
How much does Mozillion Pay Monthly Plus 310GB cost?
As of 6 October 2026, it costs £100 upfront followed by 23 monthly payments of £4. That adds up to £192 over 24 months, the equivalent of £8 a month. The upfront amount covers half the contract cost plus your first month.
Is there a credit check for Mozillion Pay Monthly Plus?
Mozillion says no credit check is needed for its Pay Monthly Plus SIM-only plans. Because you pay half the contract upfront, the provider takes on less risk than with a standard monthly contract. You still need a valid payment card for the monthly payments.
Can I keep my number on Mozillion Pay Monthly Plus?
Yes. Text PAC to 65075 from your current phone to get your PAC code, then give it to Mozillion. Your number should normally transfer within one working day of the request.
Do I get 5G on Mozillion Pay Monthly Plus?
Yes. Mozillion says all its plans include uncapped 4G and 5G speeds with no throttling, as long as your phone supports 5G and you are in a 5G coverage area. Check Mozillion's coverage checker for your postcode before switching.
Does unused data roll over each month?
No. Mozillion says unused data does not normally roll over from one month to the next. With 310GB a month, most people will not come close to using their full allowance anyway.
Can I use my Mozillion data abroad?
Yes. Pay Monthly Plus includes roaming in 41 destinations, mostly in Europe, with a fair-use data allowance that is lower than your UK allowance. Check the limit for your plan on Mozillion's site before you travel, especially if you plan to tether a laptop.
What is the difference between Pay Monthly Plus and preloaded SIMs?
The benefits are the same, and only the payment structure differs. With preloaded, you pay the full contract cost upfront. With Pay Monthly Plus, you pay half upfront and the rest in monthly instalments. Both work out cheaper than Mozillion's standard Pay Monthly SIMs.
What happens when my 24-month Pay Monthly Plus plan ends?
Mozillion says it will contact you at least a month before your plan ends. You can then choose another Pay Monthly Plus plan, switch to a different Mozillion SIM, or take your number to another network. Compare prices again at that point to make sure you are still on a good deal.
