VAT amount in GST on Purchases Report does not match that of the Balance Sheet

When a user creates a transaction, Tax Period is based on the transaction date thereby when GST Reports are run; GST Amount will be based on the transaction date.
 
Balance Sheet report, however, is based on the Accounting Period. If the transaction date is outside of the Posting Period, there will be discrepancies in the GST amount between the two reports.
 
Sample: A vendor bill dated 03/14/2012 with a Posting Period of July 2012.

On the GST on Purchase Report, GST amount will show under March 2012 however on the Balance Sheet Report, the GST amount will show under July 2012.
 
Tax Period field is currently not yet visible in transaction forms. This is logged under Enhancement 202236