Class and tags are NOT the same.

Class is Division, Department or Location; or Program or Purposes.

If you need more than one Class, you Allocate this using Splits.

I buy $400 of supplies from Staples:

Office Supplies expense account, $50, Class = Day Care

Office Supplies expense account, $150, Class = Food Bank
Office Supplies […]

Resolution for 'classes issue: 'Can you use multiple classes?' available: Yes.

The classes issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the classes issue yourself by looking for a resolution described in the article. If it is a complex classes issue or you are unable to solve the issue, you may contact us by clicking here or by using other classes support options.

For more information about resolving issues related to classes in Quickbooks/QBO or to get support for the issue 'Can you use multiple classes?', click the link below: