N.D. Cent. Code § 57-38.1-17
57-38.1-17. Other sales
57-38.1-17. Other sales
Sales, other than sales of tangible personal property, are in this state if:
1. The income-producing activity is performed in this state; or
2. The income-producing activity is performed both in and outside this state and a greater
proportion of the income-producing activity is performed in this state than in any other
state, based on costs of performance.