Hi @robert22north,
Welcome to the QuickBooks Community! You can enter your VAT registration number on the Taxes page. To get started, let's set up your VAT settings first.
Here's how:
1. On the left menu, click on Taxes.
2. Click Set up VAT button.
3. Select your filing frequency.
4. Choose your VAT accounting scheme (Standard or Cash).
Then, you'll be able to enter your VAT registration number on that same page. Then, click Save.
Also, you can run through this article about the frequently asked VAT questions: VAT - Getting Started.
Don't hesitate to get in touch with us if you have other concerns. We'd love to help. Have a great day!