If you already have a QuickBooks Online account, you can still add additional company files.  

  1. Go to https://quickbooks.intuit.com/choose-country/ Choose your country to be directed to your region specific QuickBooks Online website.
  2. Select a product (Simple Start, Essentials or Plus).
  3. Click Start Free Trial or "Buy Now".
  4. On the next screen you may get option to either continue to create free trial (Continue to Trial) or buy now for a discounted price.
  5. Since you already have an account with Intuit, click on "Add another company?" link located at the top of the screen.
  6. Enter your Email Address (User Id) and Password.
  7. Click Add new company.