Withholding tax and Items

Dear All

Kindly advice your thoughts on this...

Normally WHT tax is supplier dependent and the code given in the Supplier defaults in to the AP line, which is fine and sweet.. However, it is not good enough to manage the WHT requirements.. because

Withholding tax is applicable as per the item selection i.e cleaning services for non resident supplier will have 9% where as cleaning services for resident will have 5% per se. this means all the PO matched invoices shoould default  WHT rates as per the item chosen and all the manual lines in the AP should default items based on item/product category/other LOV's rather than defaulting one code from supplier.