Wrong tax calculated on attributes

[Heather Bee]

Just setting up new install of 1.5.6a.
Have set 1 tax rate of VAT 20%.
Store and admin set to show prices inclusive and product prices are being shown correctly on store front.
But attributes (entered excluding VAT) are being calculated with a tax of 8%.
Where is this 8% coming from? why not 20%?
Very confused.

[Heather Bee]

Solved - attribute was applying a discount.

[mc12345678]

Just setting up new install of 1.5.6a.
Have set 1 tax rate of VAT 20%.
Store and admin set to show prices inclusive and product prices are being shown correctly on store front.
But attributes (entered excluding VAT) are being calculated with a tax of 8%.
Where is this 8% coming from? why not 20%?
Very confused.

At what point in the process is this discrepancy identified?