Offline card payments on site with no signal: Square vs SumUp vs Zettle, limits and risks

Category: Tools, Materials & Tech • Niche: payments, card readers, connectivity, Square, SumUp, Zettle

Contents

• Quick answer
• Who this is for
• What each provider can do when you have no signal
• Set up Square Offline Mode step by step
• Limits, risk and chargebacks: what to watch
• Workarounds when there’s truly no coverage
• Reconciliation tips in Xero or QuickBooks
• FAQs

Quick answer

• Square supports offline card payments in the UK on most Square hardware. Transactions are stored securely and auto‑process when you reconnect. You carry the risk for any declined or disputed payments accepted offline. See Square’s UK help for supported hardware, time windows and caps. Square Offline Mode
• SumUp supports “offline transactions” on certain devices and shows limits inside the app. You also carry the risk during an Offline Session. SumUp doesn’t publish a single UK device list page, so check your device/app settings or ask support. SumUp Payment Terms
• Zettle by PayPal does not support offline card processing. You need live Wi‑Fi or mobile data to take payments. Use their Terminal with built‑in SIM to improve coverage, or switch to a provider with offline mode. Zettle help

Who this is for

• Trades who take card payments on site (builders, electricians, plumbers, landscapers) and sometimes have no Wi‑Fi or patchy 4G.
• Small contractors who want a simple, low‑risk process when the network drops and a clean accounts trail later.

What each provider can do when you have no signal

• Square: Offline Mode on Register, Terminal, Handheld, Stand and Reader models. Offline payments are stored on the device and will try to process automatically once you reconnect within the allowed window. You can set a per‑transaction cap in settings. You’re liable for any declined or disputed offline payments. Details vary by hardware. Square Offline Mode

• SumUp: Offers offline transactions on compatible devices; limits and timing appear in‑app when you enable Offline Session. Official UK documentation emphasises that you bear the risk until the payments are uploaded. If in doubt, confirm support for your specific reader. SumUp Payment Terms • SumUp readers in tough environments

• Zettle by PayPal: Requires an active connection. There’s no queued “offline” processing. Their Terminal includes a built‑in SIM that auto‑switches to mobile data, which helps on patchy sites but still needs some coverage. Zettle Terminal connectivity

Fast comparison

| Provider | True offline card mode | Upload window | Per‑transaction cap | Who carries risk offline | |---|---|---|---|---| | Square | Yes (most hardware) | Reconnect promptly; guidance suggests within 24–72 hours depending on hardware | You set a cap in settings (values shown in your Dashboard/app) | You (merchant) | | SumUp | Yes on some devices | Time window shown in‑app for your Offline Session | Limits shown in‑app | You (merchant) | | Zettle | No | Not applicable | Not applicable | Not applicable |

Sources: Square UK help page for Offline Mode; SumUp UK Payment Terms and device guidance; Zettle UK help pages.

Set up Square Offline Mode step by step

• In Square Dashboard or on your device, enable Offline Mode and set a sensible per‑transaction limit for offline sales. Keep it low for higher‑risk scenarios (new customers, large invoices).
• Confirm your hardware’s time window. On some setups that pair to a phone/tablet, you must reconnect at least every hour to continue accepting offline payments. On dedicated hardware (e.g., Terminal), you typically have longer – but upload within 24 hours to minimise declines. See the hardware‑specific notes on Square’s UK help.
• Turn on digital receipts and collect an email or mobile. If a payment later fails, you’ll need a way to contact the customer.
• Add a quick “no signal” script for your team: explain you’ll run the card now, the terminal will queue it safely, and it will complete as soon as you’re back online.

Short demo video

Limits, risk and chargebacks: what to watch

• There’s no real‑time bank authorisation offline. If a card is expired, over limit or later disputed, you’re on the hook with both Square and SumUp. Build this into your policy:
  • Set a sensible offline cap (e.g., £50–£250 for domestic jobs; only more for repeat clients).
  • For larger amounts, take a part‑payment offline and the balance later by bank transfer or once connectivity returns.
  • Check the name on the card matches the customer and collect a signature when practical.
• Reconnect and upload quickly. Both providers say to reconnect promptly so queued transactions process while they’re still valid. Don’t sign out or reset hardware until uploads finish. See provider pages: Square, SumUp.

Workarounds when there’s truly no coverage

If your site has zero signal for hours (basement plantrooms, rural plots):

• Bring connectivity with you: a 4G/5G router with a high‑gain external antenna, or keep a spare network on dual‑SIM phones. Satellite internet is increasingly viable for remote sites.
• Use bank payment links: Open banking “pay by bank” links settle fast and cost less than cards. We’ve covered set‑up and reconciliation options for Stripe and GoCardless here: Pay by bank links for trades.
• Send an invoice to pay later: If you use Zettle or are wary of offline risk, send a quick invoice or payment link to the customer while you have signal, or when you’re back at the van.

Reconciliation tips in Xero or QuickBooks

• Create a dedicated bank account in your ledger for each provider (Square Clearing, SumUp Payouts). Match payouts to this account, then transfer to your main bank when funds arrive.
• Flag offline‑mode takings with a tracking category/class. If an offline payment later fails, you can quickly identify and follow up with the customer.
• Keep fees tidy: Post fees daily or monthly via a journal to a “Card fees” expense code so your job profitability stays clear.

Simple flow to keep cashflow protected

1. Try card as normal.
2. If no signal and you have Square/SumUp offline: take a small part‑payment offline and get contact details.
3. Reconnect and confirm sync the same day.
4. For balances, send a bank payment link or invoice.

FAQs

Does Square work offline in the UK?

Yes. Square supports Offline Mode on most UK hardware. Transactions queue and auto‑process when you reconnect, within the allowed window. You set an offline cap and you carry the risk if a payment later fails. Square UK help

Does SumUp work offline?

SumUp offers offline transactions on compatible devices, with limits and timing shown in‑app when you enable an Offline Session. You’re responsible for any declined or disputed payments taken offline. SumUp Payment Terms

Does Zettle work offline?

No. Zettle requires an active connection. Their Terminal has a built‑in SIM to improve coverage, but it still needs mobile data or Wi‑Fi to process a card. Zettle connectivity

What offline limit should I set?

Keep it low unless you know the customer. Many firms set £50–£250. For bigger jobs, take a small deposit offline and the rest by bank link once you’re online.

How do I keep accounts tidy if a queued payment fails?

Use a separate clearing account for the provider, and tag offline takings with a tracking category. If a payment fails on reconnection, you’ll spot it and can chase or switch the balance to bank transfer.

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