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Specify the company, select Advance Payment as a transaction Type, and select Credit Note in Basis

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In Inventory and Services Tab fill Item (create Service Items as Rebate), Content, and Price (note that the VAT amount will be calculated on the settings in the main tab (Price include/do not include VAT): 

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The Output VAT Transaction will increase Output Tax for the period since it's an advance, but it'll reversed once you adjust the Credit Note with Receivable invoice: Image Removed. Some of the auditors believe that the
the company must generate a tax invoice to the customer in the amount of such advance, Please do as per advise of your tax consultant.

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