You want to know how to override the default sourcing for a transaction to force origin-based sourcing within AvaTax for NetSuite.
Override using the Pick Up checkbox:
- Setup > Company > Locations > Edit Location > check the Pick Up checkbox > Save.
- When the location is selected on a form, the transaction is sourced from the Location address instead of the Ship-to address.
For more information, see the AvaTax for NetSuite user guide.