HMRC has a clear set of rules to ensure that holiday homes only benefit from its more generous tax treatment when they are genuinely used as businesses, and their rules, which are tried and tested, say that the home has to be available 210 days a year to let and actually let for at least 105 days. Would there be any merit in officials at least considering whether that definition could be usefully imported to reduce the tax avoidance that clearly has been going on in this area?