Can I add superannuation as a separate item? exclusive of the GST

Hi antken187-hotmai,

You can check the GST setup in QuickBooks Self-Employed and select Exclusive of tax if this is the sales tax preference applicable on your business. Once done, go to Transactions tab and select Superannuation expense on the category of the transaction recorded. 

For your future reference, you can check on this article: Categorise transactions in QuickBooks Self-Employed.

If there's anything else I can do for you, please let me know by commenting below. I'm more than happy to offer additional assistance.