Hi there, I'm having a similar problem. 

How do I make the customer's VAT number appear on an invoice? I use a custom designed invoice template and I'm using the code <billingtaxnumber>. Unlike the other codes, it doesn't auto match. I can then tell it to match to Customer's VAT number, but it doesn't return a value. 

The one other piece of info is I haven't set up the VAT function on QBO (as I'm not yet registered), but my customer wants their VAT number to appear on their invoice. 

Thanks for your help. 

Jeremy