There are several requirements to remain in Britain after June 30.
Millions of people have used their own means to stay and work.
LONDON, June 9 - When Dutch boat captain and engineer Ernst-Jan de Groot applied for the Brexit to continue working in Britain he grew into a bureaucratic nightmare because of an online glitch and says that he is now likely to lose his job.
Under new immigration rules coming into force, de Groot faces the prospect of losing the right to work in Britain unless he can submit a visa application through the Government website by the end of June.
Following its departure from the orbit of the European Union at the end of December, Britain is changing its immigration system and ending EU citizens' preference over people from elsewhere.
While the government has processed more than 5 million applications from EU citizens to continue living in Britain, some lawyers and campaigners estimate that there are tens of thousands who, like de Groot, risk missing the deadline.
Those who succeed are not given a physical document to prove they have the right to live or work in Britain, so they remain hostage to websites when they need to prove their status at borders or when they apply for mortgages or loans.
The experience of de Groot and eight other applicants spoken by Reuters shows how Brexit has put some EU citizens at the mercy of government websites and officials, and how Britain could be inadvertently discouraging people with the skills it needs.
I am trapped in a bureaucratic maze that would even astonish Kafka and there is no exit, de Groot said. I tried everything I can think of to communicate the simple fact that their website is not functioning as it should.
De Groot, 54, has been at work in Britain for the past six years on and off.
He sails long, narrow barges from England to the Netherlands to be used as floating homes. He also spends a few months of the year building boats at a shipyard near Scotland and cruises in London in summer after a high ship is sailed around the west coast of London.
A fluent English speaker, de Groot says he follows the post-Brexit rules by applying for a foreign worker permit to allow him to work in Britain but not being resident.
The online application was straightforward until he was asked to provide a photo. On the next page of his application, which was reviewed by Reuters, said: you do not need to upload photos, and there was no option to give one.
A few weeks later, his application was rejected for not being in good standing on photos of the child he saw.
So started a bureaucratic nightmare of telephone calls, emails and labyrinthine chaos. He estimates that he has spent over 100 hours contacting government officials who he said were either not able to help or gave conflicting information.
Some officials told him that there was a technical issue that could be solved quickly. Others said there was no problem.
For each time he telephoned, de Groot said he asked the person to make a record of his complaint from the person who called him. On his last call, he said an official told him that they did not have access to individual cases, so that was impossible.
He tried to stop a new application to do the glitch but every time he entered his passport number it was connected to his first application and remained trapped in the photo upload loop.
The Home Office, the government department that administers immigration policy, did not respond to requests for comment about de Groot's case or the lack of physical documents proving the status of successful applicants.
Over the past two decades, Britain has experienced unprecedented migration. When it was part of the EU, the citizens of the bloc had a right to work and live in the country.
A desire to take back immigration was a driving force behind the campaign for Brexit in the 2016 election, with supporters calling for Britain to take back control of its borders.
Most EU citizens who want to stay in the United Kingdom will need to have applied for settled status before July. Others, like de Groot, must apply for visas to work in Britain.
Landlords, employers, the health service and other public departments will be able to ask for proof of their immigration status from EU nationals next month.
The Home Office has a reputation for targeting people who do not have the correct documentation.
The government apologised three years ago for the home office's treatment of thousands of Caribbean migrants who received basic rights, including some who were wrongly deported despite arriving in Britain decades before.
So far this year, 3,294 EU nationals were denied entry to Britain with some taken to detention centres because they could not show a correct visa or their residency status.
Lawyers, charities and diplomats say some EU nationals may be unaware they are currently to apply or are struggling to navigate the bureaucracy.
Chris Benn, a British immigration lawyer with Seraphus, a law firm contracted by the EU delegation to the United Kingdom in order to provide advice on new rules, has spent the last three years at events telling the EU citizens how to navigate the new system.
Although Benn said it would be impossible to know how many people still need to apply, he is worried that tens of thousands of people may miss the deadline and possibly a hundred thousand are going to stay.
Benn says that he is still meeting well-educated, fluent English speakers who don't realise they need to apply. He is particularly concerned with the elderly and people in new areas like those working on farms may be unaware of the rural rules.
If only a very small percentage miss out, you will have very widespread issues, he said.
While the system has worked for millions, the nine EU nationals who are unhappy with applications spoken to by Reuters say it seems that it remains overwhelming. They complain of long waits to speak to the call centre staff and, when they get through, they are not given case-specific advice.
One of them, a Spanish student in Edinburgh, told Reuters he was concerned he would be unable to complete his studies because his fixed status application in November has been put on hold.
Three days after his application, he was informed in documents reviewed by Reuters that police considered him for grave and reckless conduct - an offence in Scotland for behaviour that exposes an individual or the public to the significant risk to their life or health.
The student, who asked not to be named publicly for fear of jeopardizing career prospects, said he had never been in trouble with the police and he had no idea what the alleged investigation might pertain to.
He requested details from the Scottish police. In the answers seen by Reuters, they said their databases showed that he was not under investigation for any crime, nor is he listed in prisons.
He has approached his university, campaign groups for EU nationals and the Spanish embassy in the UK with questions concerning immigration. No one was able to stop him from the bureaucratic maze before well over sixty seconds.
The panic has been gradual and constant, he said. I end up thinking about it all the time because I could get kicked out of the country literally.
A spokeswoman for the Home Office directed questions to Police Scotland.
The Home Office did not reply to requests for comment about the student's case or complaints about call centres.
De Groot is frustrated in both ways. The company that usually employs him to captain a ship in the summer has started to look for someone else.
The diplomats are worried that the EU might have more problems if we do not have the right documents yet?
The government has said that anyone who miss the deadline will lose their right to access services such as free non-urgent healthcare and could be deported. Guidelines suggest that leniency will only be granted in certain cases, like people with a physical or mental incapacity.
Even those with legitimate status are concerned that they could still end up in immigration limbo without a physical document as proof if websites fail.
When Rafael Almeida, a research fellow in neuroscience from the University of Edinburgh, applied for a mortgage this year, he was asked to provide a share code generated by a government website to prove his settled status.
Almeida said the website was not working and he was greeted with a message: There is a problem in service at the moment. Try it again later.
After a month of unsuccessful attempts to generate the code, Almeida's mortgage broker persuaded the lender to accept only his passport as verification of identity. The website is still not working
The Home Office did not respond to requests for comment.
Almeida is worried that he will never be able to get healthcare or apply for a job, or return to Portugal to see family or friends from next month.
I am incredibly frustrated, I am in an incredibly anxious state, people who should have been taken care of this, says he said. I am a little worried for the future, just like you are. According to a public opinion, it's dangerous to compromise what you want to do with another sentence.