Why NI and income tax rates should be harmonised

I was going to write a long post about how our currently overly complex tax system is crying out for simplification and that despite the fact that there will doubtless be some anomalies that need to be ironed out, the putative harmonisation of NI and income tax rates would be a good thing.

And then I came across this post on the Adam Smith Institute blog with this table describing NI and tax rates when currently taken together that illustrates more eloquently than I could articulate in words why the current situation is crazy: