I'm here to make sure you'll be able to show the client's VAT number to your invoices in QuickBooks Online (QBO), Newage.

To start, please enable VAT in the QBO company. Then, enter the VAT Registration No. on the Customer information page. To guide you further, please follow these steps:

1. Go to the Sales menu, then select the Customers tab.
2. Click the customer's name to open the Customer information page.
3. Input the VAT number in the VAT Registration No. field.
4. Tap Save.
   

After that, include the VAT Registration No. field in your invoice template.

1. Go to Settings and then select Custom Form styles.
2. Click the Edit button or tap New style.
3. Choose the Content tab and click the upper part of the template.
4. Place a checkmark in the VAT Registration No. box.
5. Hit Done.
   

Once done, ensure to select the invoice template every time you create your invoices in QBO.

Additionally, here's an article for your reference with utilizing the templates in QBO as well as on what other information we can add: Customise invoices, quotes, and sales receipts in QuickBooks Online.

Please let me know if you have additional questions or other concerns about managing your invoices in QBO. I'll be glad to help. Have a wonderful day ahead!