BlueFolder will use the system default tax code for all of your Work Orders for all of your Customers unless you specify a customer default tax rate.
You'll want to specify a default tax rate for customers who are in areas where the tax rate differs from your default.
First you will need to add the new tax rate within the settings of your account. To do this navigate to Billing > Tax Codes. Once there you'll want to click on Add New Tax Code. Enter the new tax rate details and save changes.
Now that you have a new tax rate you can navigate back to the customer and your new tax rate will be available in the drop down field for 'default tax rate'.
After the default tax rate is populated all Work Orders for that customer will be taxed at their default tax rate.