Posting Documents That Have Their Tax Value Calculated by AvaTax
Accounting can be enabled to use Avalara's AvaTax product for the calculation of Sales and Use Tax (SUT). But it is important to note that Salesforce imposes a restriction that prevents callouts to external systems when there are pending operations in the same database transaction. (You can get more information about this restriction from the Salesforce Help topic www.salesforce.com/us/developer/docs/apexcode/Content/apex_callouts_timeouts.htm.) So if your Accounting org is enabled to use AvaTax, any existing code you have written to post sales invoices and sales credit notes may run into unexpected errors if, for example, it undertakes database updates before making the call to PostInvoice, PostCreditNote, BulkPostInvoice or BulkPostCreditNote.
If you are in this position, you can work around the issue by doing either of the following:
For information about how to setup Accounting to use AvaTax for SUT calculation, see the Accounting Help topic "Setting up External Tax Calculation".Note
The ScheduleInvoicesForPosting and ScheduleCreditNotesForPosting services can be used to post sales documents even when the org is not integrated with AvaTax. But remember that the documents are batched up for posting by a scheduled job; they are not posted immediately. For details of how to set up the scheduler, see the Accounting Help topic "Setting up the Background Posting Scheduler".Note
From V15, AvaTax can also be used to calculate tax for companies with VAT, GST and Combined record types.