How to move my simple start subscription to accountant online as I scale up my Bookkeeping business?

Good day, @rebeccahoward121.

The option to transfer a QuickBooks Online Simple Start subscription to QBO Accountant is unavailable in the program. 

Although, you can sign up for an Accountant version using a different Intuit account subscribe to a wholesale discount plan. Then, transfer your Simple Start subscription to your wholesale discount plan. This way, you can take over the billing using your firm.

Here's how to put you on wholesale discount:

1. Make sure you have added your Accountant user, then go to Settings ⚙ and select Account and settings.
2. Click the Billing & subscription tab.
3. Select the Allow billing transfer to your accountant? link.

For additional info, you can check out this article: How to take over billing for clients who currently pay for their own QuickBooks Online subscription.

You can also upgrade or downgrade your clients' QBO subscription level so they get more (or fewer) accounting tools.

Let me know if you have other questions about this topic. I'm always here to help you more. Keep safe and more power to your business!