We have 3 different sets of receipts: sales invoice, charge invoice and official receipt. We issue sales invoice for cash sales transactions, charge invoice for sales on account, and OR for collection on account. For the months of January to March 2011, we recorded the sales invoices and charge invoices in our subsidiary sales journal. However, from April 2011 to present, we record the sales invoices and ORs in our subsidiary sales journal, what would be its tax consequences? your response will be highly valued and appreciated. thank you!