Tax policy controls which products, adjustments and services are taxed. The policy is located in Administration -> Policies -> Finance -> Taxes
The "Taxes" tab allows user to define all taxes that are used in the system. The other tabs specify where exactly each tax is used.
For example, you may have Commercial leases, and you want to include tax in their billing. This can be achieved by creating a tax in the "Taxes" tab, selecting Commercial in the "Products" tab, and adding that tax to the product. You do not need to set the From/To dates, unless the tax has a start date or an expiration date.
Same logic applies to Vendor Services and Adjustments.
All Vendor Services, Products and Adjustments which are not added in this policy will have no tax.