For the purposes of the sales factor of the apportionment formula for each trade or business of the taxpayer, the term "sales" means all gross receipts derived by the taxpayer from transactions and activity in the regular course of such trade or business. The following are rules for determining "sales":
In some cases certain gross receipts should be disregarded in determining the sales factor in order that the apportionment formula will operate fairly to apportion to this state the income of the taxpayer's trade or business.
In filing returns with this state, if the taxpayer departs from or modifies the basis for excluding or including gross receipts in the sales factor used in returns for prior years, the taxpayer shall disclose in the return for the current year the nature and extent of the modification.
If the returns or reports filed by the taxpayer with all states to which the taxpayer reports under the multistate tax compact or the uniform division of income for tax purposes act are not uniform in the inclusion or exclusion of gross receipts, the taxpayer shall disclose in its return to this state the nature and extent of the variance.
Kan. Admin. Regs. § 92-12-95