How to book an invoice with negative vAT

I have an invoice from Easykit. I once paid them an advance invoice with VAT. Because they are deducting the invoice for the heat pump with the co-contractor, they are deducting the advance invoice. As a result, I have an invoice for approximately 7000 euros with -500 euros VAT and a total of 6500 euros. How do I enter something like this in Dextter?