They did have a plan for Brexit but I think it amounted to 1) eat cake 2) still have total access to mainland Europe's cake markets too. On a more serious note

They did have a plan for Brexit but I think it amounted to 1) eat cake 2) still have total access to mainland Europe's cake markets too. On a more serious note a tax plan is easier because the government only has to negotiate with itself while Brexit actually involves outside countries who are disinclined to give the UK a cushy deal.