Tax calculation not being shown properly for Purchase requisitions - 25C

In our system , we have PRs being created by business owner for requisitions made from vendors outside Canada ( UK , US) , however deliver to location is within Canada . ( Eg: Toronto Office location) . When such PRs are create the tax calculation is coming up incorrectly these vendors . An 8% tax is being applied on the PR amount , when actually for these vendor since they are outside Canada , no tax should be visible.

For procurement we use Requisition Amount ( pre-tax) , PO amount ( pe-tax) and the receipts are also created for pre-tax amounts . the only time tax is submitted is at the time of invoicing.