35 Miss. Code. R. 4-10-03-204
"Gross income" from gathering and interpreting data within and without this state may be apportioned between the states if adequate records are maintained. "Gross income" does not include receipts which constitute reimbursement by clients for the cost of easements to cross or enter land of property owners for property damage payments. In addition to services ordinarily rendered, the operator of a management company may also act as an agent for well owners in arranging for other services. In such cases, the operator is not liable for tax on receipts which represent rebilling to the owners of payments made to vendors by the operator for property purchased and services performed for owners on which the regular retail rate of tax has been paid to the vendors.
35 Miss. Code. R. 4-10-03-204