35 Miss. Code R. § 4-10-01-805
A person with a valid sales tax number who is purchasing concrete to use in the performance of a taxable service is considered the consumer of the concrete and must pay tax to the vendor at the time of purchase. Contractors who mix concrete or asphalt for use in the performance of a job owe sales tax on the value of the concrete or asphalt. Any person purchasing concrete or asphalt from an out-of-state vendor for delivery and use in this state will be liable for remitting use tax on the purchase price of the concrete or asphalt. Any person who mixes concrete or asphalt out of state for delivery and use in this state will be liable for remitting use tax on the value of the concrete or asphalt. The term "vendor", as used in this section, means a person who is mixing concrete or asphalt from raw materials either at a fixed plant site location, a portable plant or through ready-mix trucks.
35 Miss. Code. R. § 4-10-01-805