A no-deal Brexit could mean "Kolpak" cricketers are gone from the English county game by 2021, according to updated guidance from the England and Wales Cricket Board.
The Kolpak ruling means that citizens of countries that have signed European Union Association Agreements, who are lawfully working within an EU country, have the same free movement rights as EU citizens.
Kolpak signings as well as cricketers with EU passports are currently eligible to play in England without counting as an "overseas" player, employment rulings that would both be directly affected by Britain's withdrawal from the European Union.
The ECB has issued an email to the 18 first-class counties noting a series of potential implications.
One such outcome involves the United Kingdom departing from the EU on October 31 without an agreement, which has frequently been floated by incoming prime minister Boris Johnson.
In that case new Kolpak registrations would be impossible and existing deals would likely cease at the end of the 2020 season.
There are dozens of Kolpaks signed to counties, with the most high-profile including former South Africa internationals Morne Morkel, Wayne Parnell, Duanne Olivier, Simon Harmer and Kyle Abbott.
Some would be easily earn overseas deals in the event of their current status being revoked but many more would expect to leave the county circuit.