Your £10 Is on a Timer: The UK PAYG Credit Rules That Catch Low-Use Numbers

Pay-as-you-go credit feels like cash in your pocket. It isn't. On most UK networks it is closer to a shop voucher with a use-by date printed in the terms and conditions. In 2026, that matters most for the numbers we don't use much: the spare phone in the kitchen drawer, the SIM in a car tracker, the handset you keep for an elderly relative, or a second number for deliveries. Leave one alone long enough and the balance can shrink to zero — or the account can be closed and the number recycled — without a single warning that feels like a warning.

This isn't a scare story. It is a small audit. Here is how PAYG credit expiry actually works, where the traps sit, and how to keep a low-use UK number alive without turning it into a monthly subscription.

Three clocks, not one

Providers tend to run three separate timers:

1. Credit validity — how long your top-up balance lasts.
2. Account dormancy — how long the SIM can go without 'chargeable activity' before the account is restricted or closed.
3. Number recycling — how long after closure before the number goes back into the pool.

They are not the same thing. A network might let your credit sit for months but still deactivate the SIM after a period of inactivity. Or it might keep the account open but expire the credit. The only reliable answer is your provider's current terms, not a forum post from three years ago.

What counts as activity?

Receiving a text usually doesn't count. Nor does a free call to voicemail. Most definitions hinge on a chargeable event: a call you pay for, a text you send, a bit of mobile data used while off Wi-Fi, or a top-up. Some providers count a top-up as activity; others want actual usage. This is where low-use SIMs fail: the owner assumes 'it's still on' because the phone shows signal, but the network sees silence.

MVNOs often run tighter windows than the big four. EE, O2, Vodafone and Three each have their own PAYG terms, and the brands that piggyback on them — Tesco Mobile, Asda Mobile, Lebara, Lyca, 1pMobile, giffgaff and others — can set different expiry rules. A 90-day inactivity window is common; 180 days exists; some plans are more generous. Don't assume that because two SIMs use the same underlying network, their credit rules match.

The minimum top-up trap

Minimum top-ups are usually £5 or £10. That is not huge, but it adds up if you are keeping three or four numbers alive. The trap is auto-pilot: topping up £10 every few months when a £5 top-up would do, or buying a bundle you don't need just to 'use' the SIM. Bundles often have their own expiry, and unused bundle data usually does not become cash credit.

Outright dormant-account fees are rare on mainstream UK PAYG, but 'use it or lose it' expiry does the same job. If your only goal is to keep the number alive, check whether a small chargeable action is enough. A one-minute call or a standard text can be cheaper than a top-up. But read the terms: some providers only reset the clock on a top-up, not on usage.

How to check your deadline in five minutes

Open the provider's app or online account. Look for 'credit expiry', 'airtime validity', 'dormant account', 'inactive SIM' or 'terms'. If the app doesn't show a date, start a chat and ask two questions: 'When does my credit expire?' and 'What counts as activity to keep my account active?' Screenshot the answer. Then note the last date you made a chargeable call, sent a text, used data or topped up. Put a calendar reminder seven days before the deadline — not on the day.

At Simstopia, the rule we would use is simple: if the provider cannot tell you the deadline in plain English, assume the deadline is sooner than you think.

Keep a number alive without funding it forever

Use the smallest top-up that resets the clock, if a top-up is what your provider requires. Set a reminder. Make a short chargeable call or send a text every couple of months if usage counts. Keep the SIM in a phone occasionally so it registers on the network; a SIM in a drawer for a year is exactly the profile that gets swept up. Don't rely on incoming texts or Wi-Fi calling as proof of life. And if the number is only for emergencies, consider whether a cheap monthly plan with inclusive calls is actually simpler than chasing PAYG expiry.

Leaving: your credit doesn't port

If you port your number to another network, only the number moves. Leftover credit stays behind and is usually forfeited. Some providers may refund a balance in limited circumstances, but don't count on it. Use the credit before you port, or ask before you request the PAC. If you are closing the account entirely, cancel any recurring top-up or card mandate and get written confirmation.

A low-use routine that works

Write down four things: provider, last chargeable event, credit expiry date, and minimum top-up. Check once a quarter. Keep a £5 top-up in reserve rather than £20. If a provider's rules feel deliberately vague, that is a reason to switch to one with clearer terms — not a reason to keep feeding it.

PAYG is still a good home for a number you don't use much. But treat the balance as a timed voucher, not savings. The network won't ring to remind you that your £10 is about to evaporate. Your calendar will.