Custom Fields price and reductions

[amymattian]

Hi,
I am trying to get the following results with tax and calculation rules for categories applied for a product.

For example 8% reduction for price:

477,40€ normal price
-8% done with tax and calculation rule used for -8% category (applied for a product with Apply generic rules setting)
Total: 439,21€

This far all is good!

Then I add custom fields with 4 different price options/custom field options. But when the shopper chooses one (for example 22€ addon), the price is not 22€ as it should but ends up being 22€ - 8% which makes 20,24€.

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So my question is, is there a way setting the prices so that custom fields do not get the price reductions? I tried reading the documentation, but could not find a solution for this.

- Anne