Dual British nationals have been warned they may be denied boarding a flight, ferry or train to the UK after 25 February unless they carry a valid British passport.The warning by the Home Office comes amid scores of complaints from British people living or travelling abroad who have suddenly found themselves at risk of not being allowed into the UK.The problem has arisen because of a change in border controls on 25 February, when everyone travelling to the UK will need permission to travel, unless they are a British or Irish citizen or are otherwise exempt.Visitors for short stays must apply for an Electronic Travel Authorisation that costs £16.But dual nationals will, for the first time, be obliged to show their British passport to travel to the UK or pay what many believe is a punitive price of £589 for a “certificate of entitlement” to attach to their second nationality passport in order to board a flight, ferry or train.

One British woman living in Germany for years who has dual nationality said she feared her children were going to be affected by the changes, particularly her son who is due to travel to the UK in four weeks’ time.“I’m really annoyed about being treated as Brexit collateral once again with this short-notice, shortsighted, arbitrary change of the rules,” she said.While the government introduced the rules last year, she and many others feel they had not been communicated well to those living abroad and that keeping up two passports for a family is an expensive “luxury” that not everyone can afford.One British woman living in Spain for more than 30 years chose to take out Spanish citizenship because of Brexit and up to now was free to go to and from the UK with her Spanish passport.But Spain requires non-nationals naturalising to renounce their previous nationality and presenting her British passport at the airport will legally risk her Spanish nationality.

She said she is aware that many will argue she should not have renounced her British passport but that this change of rules will apply to many children of British citizens born in Spain who have never held a British passport but whose records will show as dual nationality at border control.“It seems a strange anomaly that while the UK is willing to recognise dual nationality, it refuses to recognise that a valid EU passport held by a UK citizen can give right of entry to the UK,” said Julie, who asked that her real name not be used.Another dual national born and educated in London told how he had booked a flight for a work trip in the last week and has only just discovered he may be stranded.He is British Italian but has never held his own British passport and has freely travelled around for his job on his Italian passport.He is due to fly to New York on Friday with his Italian passport but returns after 25 February and won’t be able to present immigration with an ETA or a British passport.

Asked if he had considered paying £589 for a certificate of entitlement to attach to his Italian passport, he said the weeks-long backlog made it impossible to get hold of before Friday.“I found myself having to travel at short notice and am now facing the idea that I may not be allowed back into the country,” said James, who is travelling to a museum in New York to complete logistics on works of art being lent to a gallery in Europe.A Home Office spokesperson said: “From 25 February 2026, all dual British citizens will need to present either a valid British passport or certificate of entitlement to avoid delays at the border.”They said this was part of a digitisation programme to enable a “seamless travel experience”, while also giving the government “greater power to stop those who pose a threat from setting foot in the country and gives us a fuller picture of immigration”.The EU citizens’ campaign group The 3 million called for a low-cost, one-off travel authorisation similar to one in Canada in place of the £589 certificate currently available.

“The UK already has the technology to do the same, so we urge them to act now to ensure British citizens are not locked out of their own country,” said Monique Hawkins, the head of policy and advocacy at The 3 million.If you are affected by the change and want to share your story, email lisa.ocarroll@theguardian.com