Tagging a Vat downpayment for a finance aggreement

I recently bought an asset on finance paying the vat and a deposit up front. How can I can tag the bank transaction and apply it to the correct vat amount?? it wont let me input the correct vat figure as its over 20%???

Thanks

You would need to create the invoice separately, see here for creating +20% VAT invoices.

Then you can link the payment on the bank to that invoice by tagging it, it should show up on the scan for matching amounts.