Cross-boroughs I suspect there is little correlation - you are right - but I was referring to cross-band. The context is a comparison of marginal tax rates, so

Cross-boroughs I suspect there is little correlation - you are right - but I was referring to cross-band. The context is a comparison of marginal tax rates, so the issue is: in this particular place, how much does earning an extra pound(gross) put in my pocket?' (if the comparison isnt between particular places, then I could just as well compare compare the UK to Nevada income tax - none). I would be very surprised if there isn't a strong correlation within a borough between income and band (i.e. people with higher incomes live in more valuable houses). Of course, any individual can choose to be an exception to that, but on average within a borough, those earning more pay more council tax. So pick any particular borough in the UK that you want for the comparison, but then ask 'in this borough, do those on high incomes pay more council tax, on average?' If the answer is 'yes', then that is effectively part of your marginal tax rate, albeit indirect.