Do card machines work in a power cut?

Only if they have their own power and a network connection. Some can store payments offline and send them later, up to a limit (£100 by default on Square's terminals). Many small shops simply close.

Do cash machines work in a power cut?

No. UK cash machines aren't fitted with battery backup, LINK says, and they also need a network connection.

How much cash should I keep at home in the UK?

There's no official UK figure. LINK suggests £50 per adult and £25 per child; the Netherlands advises €70 per adult and €30 per child for 72 hours. Keep more if you'd need taxis, fuel or a tradesperson.

Is Apple Pay or Google Pay a backup?

Not on its own. It needs the same terminal, network and power as a card, and a charged phone. A physical card from a second bank, and cash, are the backups.

What Happens to Your Money in a Blackout? Cards, ATMs & Cash (UK)

What stops when the power goes

Paying by card feels instant, but every tap depends on a chain: power at the till, a working terminal, a network connection, the payment company's data centre and your bank's systems. Break any link and the payment fails.

Cash machines need the same things. LINK, which runs Britain's cash machine network, told a House of Lords inquiry this year that "ATMs require power and telecommunications networks to function", and that "in the UK ATMs are not fitted with UPS", the battery backup that would keep them running through a power cut (LINK). In Spain and Portugal, it added, mobile networks failed within about 20 minutes of the blackout.

Some card terminals can take payments offline and send them through later, but only within limits. Square's offline mode in the UK accepts chip and PIN, Apple Pay and Google Pay up to a default of £100, and the shop carries the loss if a payment is later declined (Square). Mastercard says all new cards issued in Europe will work offline from February 2027, up to €200 a payment; it hasn't said whether that includes the UK (Mastercard). And no terminal works without power.

What happened in Spain and Portugal

On 28 April 2025 the Iberian grid failed in seconds. The Banco de España later measured what happened to payments (Banco de España). Compared with a normal Monday, card transactions fell by about 55% and cash withdrawals by 34%. Fewer than 4% of cash machines had backup power, and most of that lasted only 10 to 20 minutes. Large retailers with generators could approve chip-card payments offline, but small local shops "had to shutter".

Reuters reported that many large supermarkets closed because they could not take payments, that the food outlets which did open took cash only, and that taxi drivers turned away passengers who had no cash (Reuters). A year later, the Banco de España noted that some machines with power ran out of notes, while others shut down with cash still inside (Banco de España).

In Portugal, card purchases fell by 36% and withdrawals by 34%, while the average withdrawal rose from €78 to €90, according to Banco de Portugal figures reported by Lusa (Observador). People took out more money, from fewer machines.

It already happens here

Britain hasn't had a blackout on that scale, but its payment systems fail more often than most people realise. Nine banks and building societies told MPs they had at least 158 IT failures, adding up to more than 33 days of unplanned outages, between January 2023 and February 2025 (Treasury Committee). Regulator data analysed by Which? show 144 outages at ten high-street banks and Nationwide between April 2025 and March 2026 (Which?).

Visa, June 2018. A faulty switch in a data centre stopped 2.4 million of 27.6 million UK card payments over an afternoon and evening, and some shops went cash-only (Visa's letter to MPs).
CrowdStrike, July 2024. A faulty software update crashed 8.5 million Windows computers worldwide. Some UK shops, and Parliament's own catering, went cash-only (Microsoft, PA via LBC).
Barclays, January 2025. On payday and the self-assessment deadline, a mainframe fault took down the app and online banking from mid-morning until the early hours. Of the payments attempted by customers who managed to log in, 56% failed. Debit cards and cash machines mostly kept working (Barclays' letter to MPs).
Worldpay, June 2026. Power failed at one of its UK data centres and, its incident report says, the backup "failed to properly engage". Card approvals failed on and off for two and a half hours one evening, at Tesco and in pubs, some of which put up cash-only notices (Worldpay, PaymentExpert).
Google Cloud, 20 October 2026. A power failure at a London data centre meant some Revolut customers couldn't pay by card, move money or take out cash that morning (ITV News). It is on our incident clock.

Most of these weren't cyber-attacks. They didn't need to be. The Bank of England now "considers disruption to payments operations to be a financial stability issue" (Bank of England), and the Treasury Committee has told the Government it "must consider the value of physical cash in emergency preparedness" (Treasury Committee).

What other countries advise

The Government's new Be Ready checklist includes "cash (mix of coins and notes) and cards" in case "electronic payments or ATMs are disrupted", and plans for three days. It doesn't say how much (Be Ready checklist). Several European countries are more specific.

Country	Official advice	Source
Netherlands	€70 per adult and €30 per child, for 72 hours	De Nederlandsche Bank
Sweden	SEK 1,000 per adult, for about a week	Swedish Civil Defence Agency
Norway	Some cash in smaller notes, a physical bank card, and accounts at more than one bank	Norges Bank
Finland	Enough cash for three days, and accounts at two banks	Bank of Finland
Germany	Keep cash at home, because cash machines stop in a power cut	BBK, Federal Office of Civil Protection
UK	Cash and cards for three days, with no amount given	Be Ready

In the UK, LINK suggests keeping £50 per adult and £25 per child, and found that only 17% of people keep any cash at home (LINK). The Bank of England's Victoria Cleland put it simply this year: "If other systems aren't working as expected, cash is still there as a practical alternative" (Bank of England).

How much cash to keep

LINK's figure works out at £150 for a family of four, and the Dutch figure at €200: enough for food and essentials for three days. Treat that as the floor. If your household would need taxis, fuel or a tradesperson in an emergency, keep more. Our suggestion for a family of four is £300 to £500.

Small notes and coins. Shops that stay open may not have change.
Don't plan on the cash machine. Cash already makes up only 8% of UK payments (UK Finance), and the number of free-to-use machines fell from 54,599 in 2017 to 33,699 at the end of 2025 (LINK). In a power cut, the nearest working one may be a long way away.
Keep it in two places. Some in the house, some in your go bag.
Check your home insurance for its limit on cash kept at home.
Top it up after you use it. Cash spent on a takeaway isn't there for the power cut.

A money plan for three days

Cash in small notes and coins: at least £50 per adult and £25 per child, and more if you'd need taxis or fuel.
Two ways to pay: cards from two different banks, at least one of them a physical card. A phone wallet needs a charged phone and a working terminal.
Your banks' phone numbers, written down, because apps fail first.
A charged power bank, so your banking app works as soon as the network comes back.
Printed copies of the documents you'd need to prove who you are, kept with the cash.
A check twice a year: when the clocks change, top up what you've spent.

Cash isn't a relic. It's the one way to pay that doesn't depend on anyone else's systems working. Our readiness test shows how long your household could manage on its own.

When the card machines stop: what happens to your money in a blackout