How is the rate calculated? Natasha Porter Updated August 03, 2023 14:15 Follow Our system looks at your customer address and charges the appropriate tax based on the province. Related articles Will sales tax be included in my order? I purchased an ATD Press book in PDF format from ATD's website. Can I print it? Where can I access TD Podcasts? Why am I being charged sales tax? What are the requirements for a purchase order (PO)?