On the accounts payable invoice entry (before the posting of the journal) we have either a tax inquiry on the line level or a total tax inquiry for the whole journal. The level in the middle - inquiry by voucher - is missing.
Let's assume the customer enters 3 invoices in one journal and the 3rd invoice/voucher has multiple VAT rates. There is no way for the customer to check if the VAT entered on these multiple lines matches what is on that 3rd invoice.
Idea: add a tax inquiry at the voucher level in the accounts payable invoice journal.