Does AWS charge US sales tax, and if so, how does AWS determine what sales tax I'm liable for?
AWS charges US sales tax for certain AWS services where applicable. For information about AWS US sales tax policies and practices, see Tax help – United States.
If you're tax-exempt in a particular state, open a case in the Support Center. Then, attach an electronic copy of your valid tax exemption certificate to the case by using the Add attachment button.
If you're not sure whether your AWS usage is subject to US sales tax, consult your tax advisor.
Amazon Web Services tax help