HMRC. Our ridiculously complicated taxation system isn’t entirely the politician’s fault.
Tax/accountancy is my profession and has been for nearly 40 years. I fully agree it's not the politicians who foul up the wording of the laws they propose. It's the back-scene civil servants who botch the actual wording which creates the loopholes and anomalies. Some of the legal wording looks like it's been drafted by a child rather than a so-called CS treasury expert. Though that's no excuse for the MP's who should actually read and understand what they're voting for.
There was a classic a while ago. To paraphrase it, there was a section in an Act of Parliament which defined a non business asset - it was something like "a non business asset is an asset which isn't a business asset". Wow, really helpful!
We also have different definitions between capital gains tax and inheritance tax, so an asset may be a business asset for inheritance tax puposes, but not a business asset for capital gains tax purposes (or vice versa). That was never the intention of Parliament, never even discussed in Parliament. Just simply, different civil servants chose to use different definitions when drafting the different legislation, without any proper scrutiny by Parliament who just "nodded through" both sets of legislation. Then the result is obviously lots of confusion, appeals, tribunal/court challenges, etc. All would have been easily avoidable had the Treasury civil servants actually bothered to check prior definitions rather than making up their own.
Same happened with the changes to "retirement" relief for small business owners, when it changed first to taper relief and then to entreprenneurs relief. Different definitions, different conditions, etc upon each change for no obvious reason and without Parliamentary discussion. Again, simply because the Treasury law drafters didn't follow through the same "rule book" from one system to another, so not only did they change the "headline" policy which had been properly discussed/agreed, they also changed loads of "behind the scenes" wording that was never intended.