The regulator proposed changes to the FCA handbook, detailing which rules it will take responsibility for if the UK leaves the European Union (EU) without an agreement.
For example, references to EU institutions, such as the European Commission or the European Supervisory Authorities, are to be replaced with the relevant UK equivalent.
The regulator wants to know whether compliance with changes to regulatory requirements by exit day would be a challenge for firms.
And under a separate consultation, the FCA plans to allow EEA firms and funds passporting into the UK to continue operating for a limited period after Brexit as they seek full UK authorisation.
The regulator said it was working to smooth the transition out of the EU where possible.
Nausicaa Delfas, executive director of international at the FCA said: “The FCA is planning to be ready for a range of scenarios.
“Today we are publishing two consultation papers to ensure that in the event the UK leaves the EU in March 2019 without an implementation period, we have a robust regulatory regime from day one, and to ensure a smooth transition for EEA firms and funds currently passporting into the UK.
“This is consistent with our aim to provide certainty and confidence for firms operating in the UK. We welcome engagement from across the sector, as we continue with our preparations for Brexit.”
Both consultations, Brexit: proposed changes to the Handbook and Binding Technical Standards and Temporary permissions regime for inbound firms and funds, are open until December 7.