The government has published documents advising companies on what will happen if the UK leaves the European Union with no trade deal.
Britons visiting the EU could face extra credit card charges while people living abroad could lose access to their bank accounts.
Ministers said “short term disruption” is possible without a deal – which is their top priority.
Stephen Jones, chief executive of UK Finance, said: “A ‘no deal’ scenario can and should be avoided. Both the UK and our EU partners should focus on agreeing a managed exit and a clear framework for cross-border trade including in financial services.
“However, it is right that contingency plans are made to minimise disruption for consumers and businesses on both sides of the Channel in the event of a ‘no deal’.
“The government is taking a pragmatic approach to addressing critical cliff-edge issues and to ensure consumers and businesses can continue accessing vital cross-border services.
“However, these issues cannot be addressed by the UK acting alone. It is therefore vital that negotiators on both sides work together to agree solutions that prevent any unnecessary disruption and additional costs for customers in both the EU and UK.”
Source: Mortgage Introducer