There are various settings regarding your sales tax and how it is displayed, labeled and included (or excluded) within the system.
The first setting 'Set up tax', is regarding whether or not you'd like to enable tax or not. Once you've checked this box (or not), you can define your default tax label. This is referring to the way your tax is displayed throughout Commusoft. If you have specific terminology you use (Tax, Sales Tax, NY Sales Tax, etc.) you can just enter this here.
After this, you can choose whether or not the line items on your invoices will include or exclude tax by default. As much as this can be edited on each invoice specifically, you can set the blanket default here to save yourself some time. Please be aware that if you choose 'Including tax', this may have a knock-on effect on any accounting packages you may integrate with if the integration isn't supported by said accounting package.
The default tax state refers to whether you want the system to automatically take into account the tax rate from the customer's address, the job address or the invoice address (if they are different). Following this, you can decide if you want to show your tax breakdown on the invoices you create through Commusoft.