Different tax for product and attributes

I have an issue with VAT (tax) and how to set them.

I have a product, which is priced by attributes. One attribute is the price of the actual product, which has lower tax and another is a type of commission, which has higher tax rate.

Can I set different tax rates for
a) product price
b) attribute A, and
c) attribute B.
And how to do it?

There's no way to do tax by attribute without writing code. You'll probably have to set them up as separate products.

stevesh:

There's no way to do tax by attribute without writing code. You'll probably have to set them up as separate products.

Setting up separate products is unfortunately not an option in my case.

Any hints what parts of the code I need to change?

I'm not a programmer, but I'm sure it would be a lot more than changing some code. You'd have to re-write parts of the product and attributes (and probably checkout) processes. A major job, I think.

stevesh:

I'm not a programmer, but I'm sure it would be a lot more than changing some code. You'd have to re-write parts of the product and attributes (and probably checkout) processes. A major job, I think.

Major job or not, it has to be done :cry:

Would it be enough to change the functions in functions_prices.php
(+ db and admin) or do I have to make changes elsewhere?
Any advice would be great...