IPV account hitting for tax varriance -11i version

[chaitu_apps]

Iam giving the below example, which we are getting the IPV account for tax varriance.

In invoice header level tax has given as 10% and supplier site level also we have given the tax
given as 10%.
But while matching to the PO, in invoice work bench user is changing the tax rate as 0%.So at this time system has calculated 0 tax line.(it is imtend functionality and correct only)

where we attached the 10% at the invoice heade level as well as supplier site level. So system has calculatd 10% tax as a IPV account and this we can see the invoice view accounting screen only.

Can any one please suggest is it correct functionality????

Tax hierachy given at the financial options level as below

Template - 1
Po for matched invoices-2
Supplier Site -3
Financial options -4

Can any one please suggest is it correct functionality????

if need more information of this...please