You must register with the Tax Department and obtain a Certificate of Authority if you will be making sales in New York State that are subject to sales tax. New York state sales and use tax information for businesses.Learn more about registering, collecting, and filing New York sales tax returns. Up to date 2024 New York state sales tax rates. To set up a tax override, create a manual collection for the products that are tax exempt, and then apply the override to that collection. If you are not registered for GST, make purchase order which will show all prices as GSTinclusive and make no mention of GST.