The VAT Registration No. will show up on the invoice once you set up the VAT feature, JeremyAdv.

Let's set it up by following these steps:

1. On the left panel, click VAT and then select Set up VAT.
2. From the Set up VAT page, choose the Start of VAT period, Filing frequency, Reporting method, and your VAT Registration No..
3. Click Next, and then select Got it.

That should display the VAT Registration No. when you print your customer's invoice.

For reference, here's an article on how to set up and edit the VAT settings, VAT codes and the VAT rates.

Just leave another reply if you need more help with VAT in QuickBooks. Thanks.