Adding a new Sales Tax item:
Navigate to your Settings menu, click on Sales Tax Item
Click the blue Add + button to add a new Sales Tax Item
Enter the details of the item and click Save.
Note: You can use the Global default rate box to mark a default tax rate to any Customer without a specific default tax rate.
Adding Sales Tax Items to an existing Estimate or Invoice
Once you've made your Sales Tax Item, you can add it to any Estimate or Invoice by choosing the correct Tax Item from the drop-down menu.