35 Miss. Code R. § 4-10-01-306
Continuous contracts on projects embracing activities taxable under Miss. Code Ann. Section 27-65-21, which are to be carried on for a definite period of time and a definite amount, will be qualified and taxed at 31/2%. Otherwise, the determination of whether a contract is subject to tax under Miss. Code Ann. Section 27-65-21 will be made from purchase orders, work orders or invoices. Purchase orders, work orders or invoices that are a continuation of prior purchase orders, work orders or invoices will be considered part of one project. Generally, work on a project takes place in the same, adjacent or adjoining area. Transmission lines (gas, water, sewage, power, telephone, etc.) are considered a project. Amounts included in the contract for non-taxable activities (grass cutting, tree trimming, etc.) may be excluded from the taxable amount of the contract.
35 Miss. Code. R. § 4-10-01-306