Lloyd's of London is planning to confirm the details of its new EU subsidiary after a meeting next Wednesday, the same day that Theresa May is due to trigger Article 50.
The Prime Minister announced this week that she will kick off the Brexit process on the 29 March, beginning two years of negotiations before the UK splits from the rest of the EU.
A spokesman confirmed that the Lloyd's council is meeting on that date to make a final decision on where the new subsidiary business will be.
Lloyd's said last year that it would lay out its plans to move part of its business to another European city in early 2017 and subsequently promised to make an announcement before the end of March.
The insurance market was said to be looking at a shortlist of five new locations, including Frankfurt, Paris and Dublin, but is now reportedly torn between Luxembourg and Belgium.
Lloyd's chairman John Nelson, an ardent Remain supporter, has previously warned London's status as an insurance leader was at risk because of the Brexit vote. He has also cautioned that, while his organisation might need to shift some of its business away from the UK, "it won't be Lloyd's losing out, it will be the UK".
Lloyd's recently hit headlines when it banned staff from daytime drinking because alcohol has been leading to so may disciplinary cases.