"Hard Brexit is then not about giving up rules. It’s all about adopting different rules. Rules that cost jobs. And impose cost on business. And harm their cash flows, which could send many under. And which means we breach our legal obligations in Ireland, making new deals with anyone nigh on impossible. Whilst protecting UK public services from abuse will be exceptionally hard. And enforcing the law will be much more difficult. And this summary only scratches the surface of the issues. This is not project fear. It’s the reality of a ruinously harmful proposal that only the insane, the uninformed and the stupidly reckless would promote."
https://www.taxresearch.org.uk