Invoices / batches imported into Dynamics Great Plains are not calculated automatically.
Dynamics Great Plains
It is best practice to run the batch recalculation utility provided by AvaTax upon installation of the AvaTax integration for Dynamics Great Plains. You can locate the utility by following the path below:
Tools / Utilities / Avalara AvaTax / Update / SOP Tax Update Utility
Once opened you are able to enter your batch criteria and run the utility to recalculate.