Retrospective is a very dangerous tool, and it should never be used unless we’re talking war crimes tbh. And they *should* be taxed per country, not in every country else you’re looking at ridiculous levels of tax which simply isn’t fair. Let’s not forget that these megacorps produce huge amounts of revenue in this and every country, tax them so hard they leave and you’re left with nothing. No one wants that.  
	 
 
	However, let’s not forget we weren’t talking about Facebook et al, we were talking on a personal level of the individual. £500k is nothing, not when you consider the average house value these days.