INCIAP - Calculate Tax on Interco AP invoice without tax on INCIAR invoice

We have a requirement to calculate tax on the Intercompany AP invoice, without calculating tax on the AR invoice.  The AR transaction type is not taxable at all.  The AP invoice includes a default tax code on the supplier site, use offset taxes is selected and when entering a manual invoice for the supplier site, the tax code is correctly defaulting for us.  Is it reasonable to expect this to function on the Interco AP invoice as well or do I have to have the same tax on the AR invoice to calculate tax in AP?

Thanks!

Jen