Setting up
1) After you have purchased and downloaded the option, install it, then click on Setup - Network button and connect to the county database

2) On Setup p.1 - select your home state from the dropdown and click Yes for the County Tax option. Where state and county tax is combined (as in New York state), set state tax rate to 0. The county tax rate shown is a nominal rate only (no need to edit it here). The actual rate applied will be that of the customer's county to which you made the sale.

3) Click button 'County List' and enter the tax rate for each of the counties that apply them. The rates are available from your local tax authority. Flag those with exceptions and explain them so your operator knows what to enter when this county comes up on invoice.
Setup is now complete

Tax by customer
When you set up customers, check the tax that applies to them. If they are out-of-state or overseas, uncheck the box and no tax will be applied.
Where shipping addresses are used, the tax is applied depending on the location of shipping address.

Tax by product
Applies to products, inventory and service charges - if you charge for something that is NOT TAXED, set the tax rate of that item to 0.
Rate shown is nominal, no need to edit it. Actual rate will be that of the customer's county to which you made the sale. That happens during invoicing.

Invoicing
When you select the customer on the invoice, the county name and county tax rate will be set on the invoice (bottom right of picture). Click Map button to view a map of the zip code area (from 'ship to' address or, if not shown, from 'bill to' address). Map requires internet connection.

When you add a charge item to the invoice, the program checks the following:
a) is customer taxable
b) is product/service taxable
c) is County tax option enabled
If all three are true, the tax is calculated at the rate shown in county tax rate.
You can edit taxes easily with Tax button at upper left of invoice input form (also on quotes and auto-invoices)

Setting up
Reports are available that give you the option to print out either tax collected (based on payment receipts) or tax charged (based on invoices).
At left is an example, based on invoices.