Can Customers be categorised into Departments

Hello kcuz38, thanks for reaching out to the QuickBooks Community today

There isn't currently a function in QuickBooks Online to categorise customers by department. 

Depending on the information you are looking to see, you could use the location tracking feature (available in QuickBooks Online Plus, Advanced, and Accountant). 

This would let you assign a location such as a department at a transaction-level (for example, on an invoice). You can then run location-specific reports, including Profit and Loss by Location. 

As an alternative workaround, you could set up each department as a customer, and each customer within the department as a sub-customer (please note, these would post to the same default Debtors/Accounts receivable account in your CoA). 

For further information on managing customers and sub-customers in QuickBooks Online, see here. Thanks again for contacting the Intuit QuickBooks Community for support - if you have any further Q's, please get back in touch.