How many subclasses can I creat in each class?

Hello, account17. 

Thank you for reaching out to the Community. For QuickBooks Online Plus, you can create up to 40 combine classes and locations. However, for QuickBooks Online Advanced, it has unlimited classes. Though, you can only use one class per item when creating a transaction.

To learn more about the usage and limitations, you can refer to these articles:  

• Learn about usage limits in QuickBooks Online. 
• Create and manage classes in QuickBooks Online. 

Additionally, if you wish to track your transaction by class just click the link.  

Please continue to post here in the Community if you have further concerns about QuickBooks. Stay safe!