Hello Ian,
Thanks for posting on Community.
We can certainly assist with recording a 100% VAT transaction. To do this, click on the + sign and select the transaction type that you need.
One the first transaction, choose the account you want to use. For the rate, enter £1, and for the VAT code, select the 20% Standard code.
On the second line, select the same account. For the rate, enter -£1, and choose an Exempt code.The total of the invoice will be 0. You can then edit the amount in the VAT box to whatever you need it to be.
Please let us know if this helps.
Thanks,