How do I pay off the vat content only from an invoice ?

Hello there, @gwebb56760, 

Allow me to share some insights about paying off the VAT content from your invoice. 

The program is designed to use the total amount on the invoice when calculating VAT.

Since you want to record only the VAT amount, you can create a bill or expense. But I'd still suggest contacting our QuickBooks Online Customer Care Team since they can assist you with creating a transaction without a purchase price. 

For more VAT topics, you can freely browse these helpful articles.

This will get you in the right direction, @gwebb56760. 

If you need further assistance, please let me know. I'm always here to help.