In PeopleSoft 9.2 Billing can VAT CODE be automatically populated on Bill Lines?

I only see options to default the VAT CODE from header-level fields such as Type and Source. Is there a way (online bills only, no interface from OM or PC/CA) for each bill line to populate the correct VAT Code based on the service being sold? Billing Charge Code has VAT driver defaults, but does not tie to the VAT CODE at all. It's looking like VAT code would need to be entered for each bill line, if the intention is for different lines to have different VAT codes.