I was reading something on Reddit the other day. It was regarding a young lad who had made about £3 mil by investing in bitcoins in the early days. What would the implications be of him cashing out that sort of money? Is it liable to tax? Surely the banks would do some form of investigation for such a large deposit? Unfortunately I am not in a position where this is going to be something I need to concern myself with, but what would the process be for a large withdrawal like that?