Cause
The A/R Sales Tax Report is based on Invoice Date. The G/L Detail Report is based on posting date. Discrepancies can occur if the Invoice Date and Posting Date are inconsistent. Example: The Sales Tax Report shows an invoice dated 5/6/2014. The G/L Detail Report does not show the transaction on 5/6/2014. The transaction shows in the G/L on 5/21/14 which was the G/L Posting Date for that transaction.
The A/R Sales Tax Report is run by Tax Code. The transaction that matches the G/L is showing in a different tax code than expected.
Resolution
Troubleshooting Techniques:
1. The G/L Detail Report will indicate a source journal
2. Review the actual Source Journal from Sales Order or A/R (either printed or in PDF format) to determine the component invoices and invoice dates
3. Review Invoice History Inquiry to confirm posting dates and invoice dates and tax schedule assigned to the invoice
4. Review the assigned Tax Schedule in Library Master, Setup, Sales Tax Schedule Maintenance. Check to see if transaction is showing in another Tax Code