Your UK mobile number and address abroad: keeping banks and HMRC happy

Keep your UK mobile number alive, switch to app-based security where your bank offers it, and give banks and HMRC your real overseas address rather than borrowing your mum's.

It sounds like admin, and it is. But the two things that most often lock Brits out of their UK money aren't tax or Brexit. They're a security code sent to a SIM sitting in a drawer in Alicante, and a letter sent to an address you haven't lived at for three years. Sort these before you go and you'll save yourself a lot of hold music.

The short version

• Many UK banks still send one-time security codes by text, and some won't send them to a non-UK number. A working UK mobile number is often the key to your online banking.
• Roaming on your UK contract can work for a while, but it's rarely a long-term plan. A cheap UK SIM-only plan or eSIM kept just for codes is the usual answer.
• Where your bank offers approval in its app instead of by text, set it up before you leave. It works on any Wi-Fi.
• Tell HMRC your new overseas address once you've moved. The online route is through your personal tax account or the HMRC app [3][4].
• Royal Mail can redirect post abroad for up to 12 months at a time, but tracked and signed-for items won't follow you overseas [5][6].
• Using a relative's UK address as if you still lived there can breach your bank's terms and muddy your tax position.

Security codes by text: why a UK number still matters

When you log in, pay someone new or buy something online, your bank has to check it's really you. Banks call this strong customer authentication, and for many people it still means a six-digit code sent by text.

That causes three problems abroad:

• Some banks only send codes to UK numbers. If you swap to a local SIM and update your number, you may find the bank simply won't accept a foreign one.
• Texts don't always arrive while roaming. Codes can be delayed or blocked, especially on cheaper foreign networks.
• Unused numbers disappear. A pay-as-you-go number that isn't used can be suspended and recycled. Ofcom says some providers act after as little as 70 days, others after six months or longer, and it's worth asking yours exactly what counts as use [1].

If your number is recycled, someone else could end up receiving your bank's texts. That's a security risk as well as a headache.

App-based approval instead of SMS

Many UK banks now let you approve logins and payments in their app, using your fingerprint, face or a PIN, rather than by text code. If yours does, switch to it before you leave. It works over Wi-Fi anywhere in the world and doesn't care which SIM is in your phone.

Two cautions. Banks often still fall back to a text code when you set up a new phone or reset your app, so keep the UK number anyway. And set the app up while you're in the UK, where a branch can help if the identity checks go wrong.

Roaming or a cheap UK SIM?

Since 1 October 2024 Ofcom has required UK mobile providers to tell you when you start roaming, give clear, free information on costs, fair use and time limits, and explain that you can set a spend cap [2]. That's useful on holiday. For living abroad, it's not the whole story.

Some UK networks offer cheap SIM-only plans designed for low use, which suits a number kept mainly for bank texts. Compare current prices yourself; they change too often for us to list. Whatever you choose:

1. Use a dual-SIM phone, or an eSIM plus a local SIM, so your UK number stays live alongside your local one.
2. Check the plan's roaming terms for the country you live in. Receiving texts while roaming is often free, but not always.
3. Find out what counts as "use" for your provider and set a calendar reminder to send a text or top up [1].
4. Keep the SIM's PIN and the account login somewhere safe.
5. Tell your banks if you change number, while you can still receive a code on the old one.

Telling HMRC your new address

HMRC needs to know where you live, for your tax, National Insurance, State Pension and Child Benefit records. GOV.UK says to wait until you've moved before updating, then do it online through your personal tax account [3]. You can also report a change of address in the HMRC app, and if you file Self Assessment, giving your new address on the return updates your records too [4].

The Low Incomes Tax Reform Group suggests that, at the very least, you tell HMRC your new residential address and a correspondence address if it's different [7]. If you're filing a P85 or a Self Assessment return for the year you leave, your overseas address goes on that as well. Our guide to leaving the UK and the P85 covers the rest.

A few practical points:

• Signing in needs identity checks. HMRC may ask for photo ID when you sign in [3]. Set up your Government Gateway or GOV.UK One Login account before you leave, while UK-based checks are easier.
• A tax adviser or accountant can act for you. If you use one, HMRC can send letters to them, and agents can report changes on your behalf [4].
• Keep the State Pension in the loop. The Pension Service needs your address too if you get, or will soon claim, a State Pension.

Mail forwarding with Royal Mail

Royal Mail's redirection service can send your post to an address abroad. The Post Office lists international redirection at £168 for up to 3 months, £238.50 for up to 6 months and £341.50 for up to 12 months for the lead applicant, with extra people at the same address charged on top (prices checked 7 November 2026) [5].

It has limits, set out in Royal Mail's consumer redirection terms [6]:

• Special Delivery, Tracked, Signed For and parcel items can't be redirected abroad.
• Items over 25 mm thick or 100 g that appear to contain goods won't go overseas.
• Parcelforce Worldwide items aren't covered, and some official mail, including some benefit letters, won't be redirected.
• A redirection usually starts five working days after it's accepted. Renewals need at least five working days' notice, and the overall maximum, extensions included, is four years.

So treat redirection as a bridge while you update everyone, not a permanent address. Bank cards often go by tracked or signed-for post, which means they won't follow you.

Some people use a paid UK mail-scanning or virtual address service instead. These can work for letters, but many banks and HMRC won't accept them as your residential address, and they're not a way round the residence rules below.

Why a family member's address can cause trouble

It's the most common shortcut: keep everything at Mum and Dad's in Swindon. It's also the one most likely to bite.

• Bank terms. Your account terms almost certainly require your current address. Telling the bank you live somewhere you don't can be a breach, and if the bank finds out through tax reporting, it may close the account.
• Tax residence. Banks have to ask where you're resident for tax. Giving a UK address while living abroad can mean the wrong information goes to HMRC and to your new country's tax office. It won't decide your residence on its own, but it doesn't help if questions are asked. See the Statutory Residence Test explained.
• Insurance and lending. Car, travel and home insurers, and lenders, price and decide on where you actually live. A wrong address can invalidate a policy.
• Missed post. Even a kind relative won't open your HMRC letters, and deadlines don't wait for the next family visit.

A relative's address as a correspondence address, with your real overseas address on file as your home, is a different matter. Some banks allow that; ask yours.

If you're keeping your UK bank account, our bank account guide explains how banks treat customers abroad.

Sources

1. Ofcom, "Pay-as-you-go mobile: use it or lose it": https://www.ofcom.org.uk/phones-telecoms-and-internet/advice-for-consumers/advice/pay-as-you-go-mobile-use-it-or-lose-it
2. Ofcom, "New roaming alerts for UK holidaymakers" (1 October 2024): https://www.ofcom.org.uk/phones-and-broadband/bills-and-charges/new-roaming-alerts-for-uk-holidaymakers
3. GOV.UK, "Tell HMRC when you change your address": https://gov.uk/tell-hmrc-change-address
4. GOV.UK, "Tell HMRC about a change to your personal details": https://www.gov.uk/tell-hmrc-about-a-change-of-name-or-address
5. Post Office, "Redirecting your post": https://www.postoffice.co.uk/mail/redirection
6. Royal Mail, Consumer and Special Circumstances Redirection Terms and Conditions (July 2023): https://services.parcelforce.com/sites/default/files/Consumer-and-Special-Circumstances-Redirection-Teams-and-Conditions-July-2023.pdf
7. Low Incomes Tax Reform Group, "Notifying HMRC when leaving the UK": https://www.litrg.org.uk/international/leaving-uk/notifying-hmrc-when-leaving-uk

Keep reading

• Keeping a UK bank account when you live abroad
• Leaving the UK: telling HMRC, the P85 and your last tax year
• Moving abroad checklist for Brits
• Powers of attorney and managing UK affairs from abroad