Is vat not a tax? I think every government cost that is a percentage of income or spending should be calculated as your expense for the government. I think inflation also should be kept in mind as it is a hidden tax. Maybe harder to calculate.
So yes, if you spend all your money to the last penny, that would be your tax rate. But many (higher income) people do not.
When I measure my revenue, I always leave VAT out. It was never my money.