This of course would not apply to British or Irish citizens with a passport of their respective countries.
But British dual nationals who only have the passport of another non-visa country of which they are also a citizen would not be eligible for an ETA (British citizens can't apply for a visa or travel authorisation to enter the UK) and so would require to have either a British passport or a CoE-RoA stamped into their non-British passport to enter the UK.
House of Commons Library briefing: Can a British citizen travel to the UK using a non-British passport? wrote:People travelling on a non-British passport demonstrate their permission to travel by using:
their digital UK immigration permission (eVisa), if they are resident in the UK;
their entry clearance vignette sticker or eVisa, if they are from a visa national country; or
their electronic travel authorisation (ETA), if they are visiting the UK and are from a non-visa national country (for example, Australia, Canada, New Zealand, USA or an EU country).
A British dual national travelling on a foreign passport wouldn’t have any of those. They would be ineligible for an ETA, eVisa or immigration permission due to their British citizenship.
The introduction of the ETA requirement is a significant change for British dual nationals with citizenship of a non-visa national country. Previously, their non-British passport would have let them travel to the UK.
This may particularly (but not exclusively) affect many EEA citizens with British citizenship, and those from the US and the Old Commonwealth who have acquired their British citizenship by descent, who have so far entered the UK solely on their EEA/US/Old Commonwealth passports and they should look at getting a British passport or a CoE-RoA in their non-British passports.Gov.UK - Electronic Travel Authorisation (ETA) factsheet – November 2025 wrote:Do British dual citizens need an ETA?
Dual citizens with British or Irish citizenship are exempt from needing an ETA.
Dual British citizens must have a valid British passport or certificate of entitlement when travelling to the UK. UK passports can be renewed at GOV.UK
We strongly advise dual British citizens to make sure they have a valid British passport or Certificate of Entitlement, to avoid problems like being denied boarding when travelling to the UK from 25 February 2026.
From 25 February 2026, dual British citizens who cannot produce a valid British passport or certificate of entitlement will need to have additional identity checks and will not be able to go through UK passport control until their British nationality is verified.
It is worth keeping in mind that the names on all non-cancelled passports held by the dual nationals must match for the HMPO to issue a British passport in the same name.
