Try this (to be modified according to your objective) with your new tax

Code Python

# price_unit # or False # product: product.product object or None # partner: res.partner object or None

Code Python (TVA Incl)

result = ((price_unit-3.17)/1.055* 0.055 + (3.17/1.2)*0.2)

Here we have a kit with 2 components with 2 differents tax rates; one of the component has a standard price of 3.17;