Defaulting Transaction Tax on AP Invoice By System Configuration

Summary

Looking Clarification on the usage of Invoice Header Value as a Part of Defaulting Option in Payable Options

Content

Hi Team,

Need clarification on the 'Tax Profile: Party' Setup which is being used to default the Tax details on the AP Invoice. Currently we have 4 Options as a part of Default Ordering namely: Invoice Header, Supplier, Supplier Site, Payable Financial Options (Application: Payables). 

What is the usage of 'Invoice Header' as defaulting Options, does it take the Tax Details from the PO which is being matched to Invoice or there is a different source for the same ? Currently our setups are as per the screenshot attached to the Post and tax is not getting calculated consistently from one source (Sometimes it picks the amount which is on PO and sometimes it is picking from supplier).