I’ve not heard of this requirement to include the client VAT number on invoices, I’m pretty sure this is not a UK requirement. If you are reverse charging the VAT then you will need at least to obtain and verify the client’s VAT number, though it’s not necessary (from the UK perspective) to display this on the invoice. If it’s required in other EU member states then I’d say the notes box is the best place to put it.
If it becomes a more widely requested feature we may consider a label in the top right that can be switched on to display the client VAT number.
Apologies I later discovered that the client VAT number will appear automatically in the top right when it has been saved in the client settings and providing the client is marked as VAT registered in another EC member state at the time the invoice is raised.
