“the legislative intention is that insufficiency of funds can never of itself constitute a reasonable excuse, but that the cause of that insufficiency, ie the underlying cause of the default, might do so. The difficulty which then arises is that Parliament has not specified what underlying causes of an insufficiency of funds which lead to a default are to be regarded as reasonable or as not being reasonable. Prima facie the legislative intention is the same as in the context of s 33(2)(b). This is that, save in so far as Parliament has given guidance, it is initially for the commissioners to decide whether the underlying cause constitutes a reasonable excuse and for the tribunal to decide this on an appeal. That said, there must be limits to what could be regarded as a reasonable cause. Nolan LJ, as I read his judgment explaining and expanding on his judgment in Customs and Excise Comrs v Salevon Ltd[1989] STC 907 , is saying that if the exercise of reasonable foresight and of due diligence and a proper regard for the fact that the tax would become due on a particular date would not have avoided the insufficiency of funds which led to the default, then the taxpayer may well have a reasonable excuse for non-payment, but that excuse will be exhausted by the date on which such foresight, diligence and regard would have overcome the insufficiency of funds.”
“Scott LJ…is of the opinion that the underlying cause of the insufficiency of funds must be an 'unforeseeable or inescapable event'. I have come to the conclusion that this is too narrow in that (a) it gives insufficient weight to the concept of reasonableness and (b) it treats foreseeability as relevant in its own right, whereas I think that 'foreseeability' or as I would say 'reasonable foreseeability' is only relevant in the context of whether the cash flow problem was 'inescapable' or, as I would say, 'reasonably avoidable'. It is more difficult to escape from the unforeseeable than from the foreseeable.”