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The Documents that are included in the Payable and Receivable 
Receivable boxes are available in the details of the of each lines of the Return document.
2) Calculation of VAT Liability is showing the Payable and Receivable VAT figures on date , BUT not for the period.
These figures are coming from the closing balance of Current VAT Payable and Current VAT Receivable GL accounts, you can check it from:
