280-20-25 R.I. Code R. § 9.13
All C corporations shall maintain documentary evidence of all market sourcing determinations. A taxpayer's application of the rules set forth in this Regulation shall be based on objective criteria and shall consider all sources of information reasonably available to the taxpayer at the time of its tax filing including, without limitation, the taxpayer's books and records kept in the normal course of business. A taxpayer's method of assigning its receipts shall be determined in good faith, applied in good faith, and applied consistently with respect to similar transactions and year to year. A taxpayer shall retain contemporaneous records that explain the determination and application of its method of assigning its receipts, including its underlying assumptions, and shall provide such records to the Division of Taxation upon request. Failure to keep such records may result in market sourcing determinations by the Tax Administrator. In any case in which a taxpayer fails to retain contemporaneous records that explain the determination and application of its method of assigning receipts, including its underlying assumptions, or fails to provide such records to the Division of Taxation upon request, the Division of Taxation may treat the taxpayer's assignment of receipts as unsubstantiated, and may adjust the assignment of such receipts in a manner consistent with the applicable rules in this Regulation. Such determinations by the Tax Administrator shall be presumptively valid. The burden shall be on the taxpayer to maintain necessary evidence supporting classification of all income and all information related to calculation of Rhode Island income. The record keeping requirements of this Regulation are not intended to discourage taxpayers from refining methods of approximation based on demonstrably improved systems of tracking information.
280 R.I. Code R. § 280-RICR-20-25-9.13