You can apply for a sales and use tax permit at the Mississippi Department of Revenue’s TAP site. Additional information is found here. Once the permit is granted, the Mississippi DOR will send your permit and information about how to file. The state requires you file online if you report more than four rates of tax, have more than one sales tax accounts, or are subject to certain fees and taxes. See reporting requirements.
If you do not file online, 30 days before the sales tax filing due date a pre-addressed form will be mailed to you.