WTO law does not generally prevent WTO members from adopting new tax measures which depart from the norm.
In the current febrile political atmosphere, it sometimes feels as if we need a daily, if not hourly, weekly tax brief to keep you up to date with all that is happening with Brexit. Indeed, it would not be surprising to find that in the time that you take to read this piece everything will have changed again. But one thing is certain. UK businesses will not be shutting shop at 11pm on 29 March 2019. But how will they trade once we have left the EU?