Purchase Order and Payables Invoice Calculating Tax Despite Selecting VAT ZERO

Hi All,

We have a situation where while creating PO (not based on requisition), we are selecting tax classification as VAT ZERO. But PO is still calculating tax. Further to this when we create invoice for same PO, it is automatically selecting VAT ZERO but also calculating tax as well. Obviously we select VAT ZERO, then there should be no tax on PO and its relevant invoice. But tax is still being calculated. Any idea how we can address this issue?

We have another BU which is not calculating tax when selecting VAT ZERO. This is fine.

Thanks in advance to everyone for their suggestions.