Sometimes tax rates change. There are two strategies to accomplish this. You can create new tax rates for the new rates and switch them over at a given time or you can simply modify the existing tax rates. By modifying the existing tax rates none of your products or add-ons need to be adjusted and the edit will be presented to the user on all subsequent purchases. Navigate to Shop Settings > Tax Rates section to find your list of current tax rates. If you do not see any active tax rates you may need to create a tax rate or all existing tax rates are archived.

Select Edit from the Actions menu for the tax rate you wish to edit. 

Modify the fields presented and when finished select Save Changes