We often need to calculate the price of an object before tax when we only know the price after tax and what tax was applied. For a single tax it is simple, divide by (1 + Tax%)
i.e. 10% tax on price after tax of 10% = 110 / (1 + .1) = 100
However, I am having a problem when there are multiple taxes applied, and some are compound taxes. i.e.
100 + 10% VAT + 10% Compound State = 100 + 10 + 11 = 121, so how do I calculate backwards.
To add to the complication, sometimes the second tax is not compounded, i.e.
100 + 10% VAT + 1-% State = 100 + 10 + 10
To further complicate this, I have an example where there are three taxes, one VAT type tax, and two withholding taxes, again these taxes can be compounded or may not be.
In each case I know the tax rules, and the after tax price, and need to calculate the pre-tax price.
Any help would be greatly appreciated. I have spend 2 days playing with Excel, but the final equation escapes me.