Many European Union nationals who thought they would be immune from the impact of Brexit because of their residency in the UK are finding that this is just not the case.

To qualify for UK permanent residency, an EEA national needs to have lived here, in the UK, for five years continuously – during which time they need to have been either in employment, self-employed, engaged in studies or self-sufficient. If self-sufficient, they must not have been reliant on public funds.

To the surprise of many and the alarm of some, the law provides that if for part of the five-year period required to qualify for permanent status an EEA National was not economically active, then they needed comprehensive sickness insurance (CSI).

Even though many of those affected were fully entitled to use the NHS, it transpires that having CSI – effectively a private health insurance policy – is a requirement for any time that an individual was not economically active.

In pictures: European parliament Brexit discussions Show all 12 1 /12 In pictures: European parliament Brexit discussions In pictures: European parliament Brexit discussions European commission member in charge of Brexit negotiations with Britain, French Michel Barnier listens at the President of the European Commission Jean-Claude Juncker speaking at the European Parliament in Strasbourg Getty Images In pictures: European parliament Brexit discussions Frank-Walter Steinmeier, President of the Federal Republic of Germany, delivers his speech at the European Parliament in Strasbourg EPA In pictures: European parliament Brexit discussions European Union's chief Brexit negotiator Guy Verhofstadt, President of the Group of the Alliance of Liberals and Democrats for Europe (ALDE), addresses the European Parliament during a debate on Brexit priorities and the upcomming talks on the UK's withdrawal from the EU Reuters In pictures: European parliament Brexit discussions Michel Barnier, European Chief Negotiator for Brexit reacts during a meeting at the European Parliament in Strasbourg EPA In pictures: European parliament Brexit discussions Member of the European Parliament and former leader of the anti-EU UK Independence Party (UKIP) Nigel Farage wears socks with Union Jack flag at the European Parliament in Strasbourg Getty Images In pictures: European parliament Brexit discussions Nigel Farage, United Kingdom Independence Party (UKIP) member and MEP, addresses the European Parliament during a debate on Brexit priorities and the upcoming talks on the UK's withdrawal from the EU Reuters In pictures: European parliament Brexit discussions European commission member in charge of Brexit negotiations with Britain, French Michel Barnier gestures during speeches at the European Parliament in Strasbourg Getty In pictures: European parliament Brexit discussions The President of the European Commission Jean-Claude Juncker (L) speaks with European commission member in charge of Brexit negotiations with Britain, French Michel Barnier at the European Parliament in Strasbourg Getty In pictures: European parliament Brexit discussions European Union's chief Brexit negotiator Guy Verhofstadt, President of the Group of the Alliance of Liberals and Democrats for Europe (ALDE), addresses the European Parliament during a debate on Brexit priorities and the upcomming talks on the UK's withdrawal from the EU Reuters In pictures: European parliament Brexit discussions Member of the European Parliament and former leader of the anti-EU UK Independence Party (UKIP) Nigel Farage gestures during speeches at the European Parliament in Strasbourg, eastern France, on April 5, 2017. The European Parliament will on April 5 lay down its "red lines" for negotiations over a Brexit deal, on which the assembly will have the final say in two years' time. / AFP PHOTO / Sebastien BozonSEBASTIEN BOZON/AFP/Getty Images Getty In pictures: European parliament Brexit discussions German president Frank-Walter Steinmeier delivers a speech during a plenary session at the European Parliament in Strasbourg Getty In pictures: European parliament Brexit discussions The European Parliament in Strasbourg, eastern France Getty Images

Despite the Government passing laws on CSI, it has been very poorly publicised, and many are only just finding out that it exists. It is a European wide requirement, but has been largely sidelined until it became an issue in the build-up to Brexit.

Sadly, and unusually for the EU, what has become clear as people have started to come forward is the legislation penalises women. In fact, it is fantastically discriminatory. This is for the simple reason that women more often take employment breaks for maternity and child-rearing purposes.

With many economic migrants tending to be young, there are two typical scenarios; the first being a woman who comes to the UK with her spouse to work and then chooses to start a family. The second scenario is that of a single woman who comes across to work, and then finds a partner and chooses to start a family. Although these women have often been self-sufficient during this time, without CSI for the period not in work they no longer qualify for permanent residency.

In my experience, this has left many women with spouses and children settled in this country, often for many years, who are now learning that they do not have the accrued residency needed to remain in the country.

There are reports too of large numbers of students being affected, with universities not making students aware of the CSI requirement – no doubt because they weren’t aware themselves.

Theresa May: Corbyn would be 'naked and alone' on Brexit

Many will rightly argue that the reasoning behind the CSI requirement is sound. It is the fact that so many EEA nationals here in the UK had no idea that it even existed that is causing such contention.

The Home Office has previously stated that the Government will not remove EEA citizens from the country if they do not have CSI. However, new regulations were introduced as recently as February this year, which suggest that the Home Office can remove anyone it doesn’t consider to have the right to reside in the UK. The status of those affected is far from clear. Commentators argue that the Home Office has indicated CSI is not necessary but those indications are far from sufficient and practitioners are not finding that to be the case.

Of course, there are other avenues those affected can explore. Article 8 of the Human Rights Act could offer protection to those who have put down firm roots in the UK, with friends, family and/or work. Others may have the right to visas related to their marriage or children. Some may have a case on the grounds of the length of time they have been here.

What can’t be ignored, however, is the immense distress this can cause – not least because of the uncertainty, but because female EEA nationals had no idea that their residency could be at risk because they gave birth at some point during their stay in the UK. It beggars belief that this would not have been considered when the government considered the permanent residency of EEA nationals post-Brexit.

With so many people caught out, and with the government currently unclear on how they intend to document everyone here already, an amnesty could prove the only sensible way forward. The legislation is discriminatory against women, and a country leaving the EU wasn’t adequately factored into it. The UK must either grant amnesty to those nationals – or face a huge backlash post-Brexit.