We charge sales tax based on your state's tax law, Ndinh. You can qualify as sales tax exempt, though.
You'll have to apply for the sales tax exemption. This way, you'll not get charged sales tax on your account.
You can check this reference on how to apply for State sales tax exemption. Once you all have the necessary documents, you'll have to fax them. The number is also available in the article.
If there's anything else that we can do for you, please don't hesitate to let us know.
