Safeguards against retrospective taxation

In a written statement on 31 October 2019 announcing a proposal for a retrospective tax law relating to HMRC’s use of automated processes to serve notices (tinyurl.com/y5wlg2ox) the then financial secretary to the Treasury Jesse Norman declared that the UK government was ‘committed to doing what is necessary to protect the exchequer maintain fairness in the tax system and give certainty to taxpayers’. The retrospective nature of the proposal must have been on his mind in reaching this conclusion since he was also at pains to point out that the government ‘introduces legislation with retrospective effect only where necessary’. This raises an important question: exactly when is legislation with retrospective effect necessary? Put another way how can retrospective tax rules protect the exchequer and treat taxpayers fairly at the same time? And should it fail to achieve this balance how should that equilibrium be restored?...