Clients of UK-based financial services firms who are themselves based in the UK are "unlikely" to be affected if there is no deal over Britain's departure from the European Union.
In a technical notice published today, the government has set out how the financial services sector will be affected in the event of a no-deal Brexit.
The government has said it will seek to minimise disruption and ensure continuity of financial services provision.
One example of this was the temporary permissions regime, which will allow EU-based firms currently passporting into the UK to continue operating for up to three years after Britain leaves the EU in March 2019.
The government also said it was giving regulators more powers to allow them to phase in post-exit rules, which will give companies time to adjust and avoid "cliff-edges".
The document said: "For UK-based customers accessing domestic services in the UK provided entirely by UK-based providers, there is unlikely to be any change as a result of exit.
"If UK customers will be affected by their firm’s planning for exit, then this should be clearly communicated to customers by the firm."
It added that UK-based customers of EU-based firms will be protected by the temporary permissions regime but it's UK citizens living abroad, who use UK firms operating in the EU, who were likely to be affected most.
One example it gave was that EU-based clients would no longer be able to use the services of UK-based investment banks, and UK-based investment banks may be unable to service existing cross-border contracts.
The government said it was not able through unilateral action to fully address the risks faced by these people but said it was working with the EU to address this issue.
Dominic Raab, the secretary of state for exiting the EU, said: "I am still confident that getting a good deal is, by far, the most likely outcome.
"The vast majority, roughly 80 per cent, of the Withdrawal Agreement has now been agreed, and we are making further progress on those outstanding separation issues.
"And at the same time, naturally we have to got to consider the alternative possibility, that the EU does not match our ambition and pragmatism, and we do not reach a deal.
"Let me be clear about this. This is not what we want. And it’s not what we expect. But, we must be ready."