UK citizens are using a legal loophole to bypass immigration rules in order to bring relatives into the country, reports the BBC.
The technicality means that relatives who have worked in another European country for at least three months can be considered under EU law rather than UK law.
The technicality is called the 'Surinder Singh route', named after a famous court case involving immigration law. Essentially it allows non-UK citizens to avoid UK legal requirements that a family member must earn more than £18,600 per year in order to come to the UK.
Under the Surinder Singh route, the UK citizen can travel to another European country and, by working there for three months, can prove that they are 'exercising their EU treaty rights'.
Under EU treaty law, a citizen can move to live and work in any other EU country, including the UK, and can bring their family with them even if they are not UK or EU citizens themselves.
According to a non-UK citizen interviewed by the BBC, the details of the Surinder Singh route are not publically available and the UK Border Agency does not notify citizens of how to use the law to their advantage.
"My friend said it's not publicised," Sarah Pitard told the BBC.
"They don't make it easy because they don't really want anyone to know about it."
The EU laws allow French or Germans living and working in the UK to bring their non-EU partners with them without having to meet UK legal requirements. The laws also similarly benefit UK citizens looking to work elsewhere in the EU.