Existing Purchase Orders, tax implications
Upgraded configuration from 11i to 12.1.2. eBtax uses the STCC regime determination template. No surprises in tax functionality except all suppliers must be set to "Calculate Tax" if auto-tax is to be expected. Support provided a simple script for this.
The problem is, that per white papers, my client will not be able to add new locations such as a new warehouse because STCC does not recognize new locations. So the upgrade eBtax is severely limited.
I can and have implemented eBtax on a fresh install, but doing so on an upgrade would require all open, unmatched purchase orders and releases to be cancelled / closed and copied to new PO's because the tax entries from the upgrade in purchasing would not be compatible with the tax engine functionality when regime determination is changed for STCC to "Determine Applicable Regimes".