[LONDON] Even one-day work assignments to the European Union are emerging as a source of worry for London-based financial professionals.

UK bankers, like many others, will face restrictions on journeys of just a few hours to the EU if Britain crashes out of the bloc on Oct. 31. Companies could face fines and other penalties if they're caught with employees who lack permits for paid work; employees could even be stopped at the border.

"This is going to be a live issue for financial services because of travel between hubs," Seema Farazi, partner and head of financial-services immigration at the consulting firm EY, said in an interview. "This is a sea change from decades of free working for UK nationals in the EU who will find that even simple activities such as remote working will carry a high risk in much of the EU27."

The UK and EU have taken steps to ensure that travel itself can continue if Prime Minister Boris Johnson carries through on his promise of leaving the EU with or without a deal -- "come what may" -- on Halloween. The EU, for example, amended a regulation to allow visa-free travel to UK nationals for short stays of 90 days in any 180-day period.

The problem arises because some EU member states require a visa to do paid work during such short stays.

Luxembourg, for instance, allows short-term visitors to speak at conferences, negotiate contracts and attend company board meetings. Other activities, such as trading, portfolio management and systems testing could require a permit, according to Ms Farazi. On the other hand, Germany has a three-month transition exempting British citizens from needing a visa to work.

"People are not connecting the dots between a sudden exit and the implication for short-term business travellers," Ms Farazi said. "It often takes something to go wrong, such as a CEO being refused entry at a border."

The Confederation of British Industry, the UK's biggest business lobby group, warned last month that there could be "immediate overnight disruption" for UK business which rely on sending fly-in, fly-out workers to the EU for short-term work. The UK and EU need to strike an agreement on travel or risk "significantly and permanently" damaging businesses.

For banks, the travel restrictions represent another sign that the EU wants firms to hire more people locally.

A spokesman for the European Commission, the EU's executive arm, declined to comment. The commission has said for months that it won't lessen the blow to the UK of a no-deal exit by giving Britain the same ability to operate in the bloc as it has currently.

BLOOMBERG