Reduced to essentials, it is clear that the tax system is now so complicated that even the revenue themselves can not understand the system.
It is a matter of urgency that the UK simplifies the tax system. Apart from anything else, the mistakes that are being made cost millions, even billions, of Pounds to put right.
There are plenty of models out there, but speaking from an Estonian perspective, the simpler the tax code, and the easier it is to calculate and to pay, then the more tax revenue is raised.
Of course, that then allows the rates of taxation to be lower for any given level of revenue.