The FCA will take a "proportionate and pragmatic" approach to reporting supervision on Brexit day should the UK leave the EU without a deal on 31 October.
In a statement, the UK's financial regulator reminded firms to take "reasonable steps" to continue to report transaction costs in line with Mifid and the Emir trade reporting rules.
"Leaving the EU during the working week could pose operational challenges for firms," the regulator acknowledges.
Leaving the EU during the working week could pose operational challenges for firms"
FCA international executive director Nausicaa Delfas said: "The FCA has been preparing to ensure UK financial services are well placed if the UK leaves without a deal. Today, we have set out steps certain firms need to take - it is important that firms are as prepared as possible if there is a no-deal exit, and that they are aware of what they need to do."
Britain remains a long way from getting a final Brexit deal and the next few days will be critical if it is to agree departure terms with the European Union, the BBC cited a source at prime minister Boris Johnson's office as saying.
Negotiators for Britain and the EU have entered intense talks over the weekend to see if they can break the Brexit impasse after Johnson and his Irish counterpart Leo Varadkar held talks this week and agreed they could see a pathway to a possible deal.
A spokesman at Johnson's office declined to comment.
In a briefing to EU ambassadors on Sunday evening, the EU's chief negotiator, Michel Barnier, raised the prospect of the talks having to continue after the forthcoming leaders' summit on Thursday, such was the lack of progress.
Barnier told diplomats for the member states that the latest British customs proposals for the Irish border remained an "untested" risk that the bloc could not countenance. He said that it would require a fresh "political impulse" from Boris Johnson for a deal to be realisable this week.
One diplomat from a major member state insisted the UK "must move quickly" if it wants an agreement signed off at this week's summit, adding: "The clock is ticking."
This Monday, the Queen started her speech in Parliament by saying the government's priority "has always been to secure the United Kingdom's departure from the European Union on 31 October".