I am a small business. How do I create a company (personal) and a company (business) under my Quickbooks Online account? Surely I will not have to pay additional money.

QuickBooks Online requires a separate subscription per business or account, BASureShot.

This means that we're unable to create a new account or company without signing up for a new QBO subscription. If you'd like to proceed, follow these steps on how a secondary account under the same login:

Go to the QuickBooks pricing page and select which subscription you want your personal account. This opens one of two experiences:

• If you're signed in to QuickBooks, confirm which account you want to sign in with. If the account displayed is the one you want to use for the new company file, select Yes, that’s correct.
• If you haven’t signed in recently, create an Intuit account. Don't fill this out unless you want to connect your new company file to a new account. Instead, look for the Adding a company to an existing account? section and select the Sign in link. Sign in with the user ID and password you already use for QuickBooks.

Once done, you can follow the steps on to switch between QBO accounts: Switch Between Company Files.

The Community is always here if you need anything else. 

@BASureShot 

One QBO account is for one company file. You may manage branches/divisions by utilizing the Class/Location feature available in QBO Plus and Advanced. Otherwise you should open a new account.

https:// quickbooks.grsm.io/US

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As another option, consider switching to QB Desktop. You may have multi company files with a one time license. QBD 2021 Premier for 1 user worth $499 thru a partner.