O2's spend cap lets you put a hard limit on out-of-bundle charges each month, so your bill can't spiral beyond what you've agreed to. You can set it anywhere from £0 up to £100 or more, and change it at any time through your My O2 account or the My O2 app. The default cap on most major UK networks, including O2, sits at £40.
The cap applies to extra charges you run up outside your monthly allowance: think premium-rate calls, extra data, or international calls. It sits on top of your base plan cost, so it does not reduce what you already pay each month. As an O2 Community member explained, a £20 spend cap on a £17 monthly plan means your total bill could reach up to £37 (£17 + £20) before anything gets blocked.
Once you hit 100% of your cap, O2 stops further chargeable out-of-bundle usage. As O2 Business support states directly: "If the Spend Cap is set at £0 or once it reaches 100%, any further chargeable out-of-bundle usage may not be possible."
Setting the cap to £0 is the strictest option. It blocks all chargeable extras from the start of your billing period, which is useful if you want to guarantee your bill never exceeds your base plan cost. For most people, something between £10 and £40 gives a reasonable buffer without the risk of a large surprise charge. The £40 default is a reasonable starting point if you occasionally go over your allowance but don't want runaway costs.
Spend caps on all major UK networks (EE, O2, Vodafone and Three) can be set anywhere from £0 to £100 or more, according to connection-technologies.co.uk.
One thing to keep in mind: the My O2 app updates spend cap usage data daily rather than in real time. That means a burst of usage late in the day may not show up until the following morning. If you're close to your limit, treat the displayed figure as a rough guide rather than a live counter.
On O2 Business, the same 100% threshold applies. Once the cap is reached, further chargeable out-of-bundle usage is blocked for that billing period. Business account holders can manage caps through the O2 Business portal, and individual user caps can be reviewed separately from the overall account settings.
## Quotations > If the Spend Cap is set at £0 or once it reaches 100%, any further chargeable out-of-bundle usage may not be possible. > — O2 Business Support (O2 Business Help & Support) (https://www.o2.co.uk/business/support/accounts-and-billing/spend-cap) > A spend cap of £20 means his monthly bill COULD be up to £37 (£17 + £20). My o2 tends to update daily rather than instantly > — O2 Community user (O2 Community forum) (https://community.o2.co.uk/t5/Pay-Monthly/What-does-a-Spend-Cap-cover/td-p/1236570) ## Frequently asked questions ### how do I set up a spend cap on O2 You can set up a spend cap on O2 through your My O2 account online or using the My O2 app. You can choose any amount between £0 and £100 or more, and change it at any time. The default spend cap on O2 is £40 per month. ### what does O2 spend cap cover The O2 spend cap covers out-of-bundle charges like premium-rate calls, extra data, and international calls. It sits on top of your base plan cost, so a £20 spend cap on a £17 monthly plan means your total bill could reach up to £37 before charges are blocked. ### what happens when I reach my O2 spend cap Once you hit 100% of your spend cap, O2 stops further chargeable out-of-bundle usage from going through. If you set your spend cap to £0, no chargeable extras are possible from the start of your billing period. ### how often does O2 update spend cap usage O2's My O2 app tends to update spend cap usage data daily rather than in real time, so there may be a slight delay before charges appear in your account. ### can I set my O2 spend cap to zero Yes, you can set your O2 spend cap to £0, which is the strictest option available. This blocks all chargeable out-of-bundle usage from the start of your billing period and guarantees your bill never exceeds your base plan cost. ## Sources 1. [Spend Cap Guide: Manage Mobile Costs in 2026 | CT](https://connection-technologies.co.uk/blog/how-do-i-manage-my-mobile-spend-caps) (connection-technologies.co.uk) 2. [Spend Cap | Help & Support | O2 Business](https://www.o2.co.uk/business/support/accounts-and-billing/spend-cap) (www.o2.co.uk) 3. [Solved: What does a Spend Cap cover? - O2 Community](https://community.o2.co.uk/t5/Pay-Monthly/What-does-a-Spend-Cap-cover/td-p/1236570) (community.o2.co.uk)