Hi there, debra20.
We're unable to create a new tax agency in QBO UK. All vat amounts are automatically defaulted to HMRC.
You'll want to consider using a third-party app that can be integrated in QuickBooks Online. Here's how to look for an app:
I'd also like to share these articles about tracking VAT for more details and reference in the future:
The Community is always here if you need anything else.