To enter VAT on a transaction, simply enter the actual amount of VAT payable or receivable in the VAT boxes in the transaction entry dialogs.

Screenshot of a section of a transaction entry dialog
To quickly calculate VAT at the standard rate, press the * key when you are in the VAT box. If a transaction is zero rated, exempt, outside the scope of VAT or from an unregistered supplier, leave the VAT box blank or enter zero.
There is no option in the transaction entry dialogs to specify that a transaction is outside the scope of VAT. Instead, this is automatically determined based on the analysis account(s) selected (for more information on this, see the Net value of transactions topic).
Please note that when you enter invoices using the sales and purchase invoice dialogs, the VAT is entered when you enter the invoice. No VAT is entered when you enter the subsequent payment, even if you are operating the VAT cash accounting scheme. Otherwise, you would be accounting for VAT twice.