https://en.wikipedia.org/wiki/Common_Consolidated_Corporate_...
Companies should have never been taxed based on a virtual, and fundamentally nonsensical, figure as the location of their headquarters. They should be taxed based on substantial things, like (the location of) capital, labour and sales. This is what CCCTB establishes. States are still free to set the tax rate as they wish. It's just that then the companies can't escape with the turnover money to another state, essentially robbing the state where the profit was generated.
This is the most important tax legislation of this day. No other debate about taxes, like the rate itself, or harmonisation of the rates across states, makes sense before this gets implemented. The reason is that now the tax rate is evadable and only stifles local/small businesses who don't/can't cheat. Sadly, there are few states that are successfully blocking this: Netherlands, Ireland, Malta, etc. But I hope to see this one day.