How do I get the vat registration number onto invoices? there is no provision to provide it in the company profile.

Hi there, @der-bur-btintern. 

I'm here to help you add your VAT number to your invoices with QuickBooks Online (QBO).

To get started, you'll need to enter your VAT registration number on your VAT centre. Once done, this will automatically be populated when you run invoice preview. Here's how:

1. Go to the Taxes menu and choose VAT.
2. Select the Edit VAT dropdown and select Edit settings.
3. From the VAT registration number field, enter your information.
4. Once done, click Save. 

After that, let's check your invoice template settings to see how the VAT registration number will populate. Let me guide you how:

1. Navigate to the Gear icon and select Custom form styles.
2. Choose the Edit button on the template you use. 
3. Go to the Content tab and click the Header.
4. It will show how the VAT registration number is displayed on the invoice. 

For more details about modifying your invoice forms, check out this link: Customise invoices, estimates, and sales receipts in QuickBooks Online.

Check out this link to run the Accounts Receivable ageing summary report to have a list of your customers’ outstanding balances. This will show you how much are still due and how long they're past due. 

Please don't hesitate to comment if you have any other questions about adding your VAT registration number to your invoices. I'm ready to help in case you need one. Have a great day ahead.