2.41 Separate accounting method. (1) When

the separate accounting method is used, separate records must be kept of sales, cost of sales and expenses for the Wisconsin busi- ness as distinct from the remainder of the business. Overhead items of income and expense must then be allocated to the busi- ness within and without Wisconsin upon a basis or combination of bases justified by the facts and conditions. For example: the ratio of Wisconsin sales to total sales usually represents a satis- factory basis for a merchandising business, while the ratio of di- rect cost of material and labor in Wisconsin to the total gives a more accurate result for a construction business. (a) Federal income taxes are based upon income and should, therefore, be allocated to Wisconsin business on the basis of in- come. Federal income taxes are deductible for income years through 1974 only on the cash basis, and the allocation to Wis- consin business for any year, therefore, must be based upon the ratio of income within Wisconsin to the total income of the year on which the federal income taxes are assessed, even though that ratio differs from the ratio of the year in which the taxes are actu- ally paid. Federal income taxes are not deductible for income years 1975 and thereafter. (b) The relationship of the general overhead items to Wiscon- sin operations will determine whether the home office income and expense should be allocated to the Wisconsin business. Mis- cellaneous income, such as income from intangibles and income from tangible property used in the business, and such overhead items as officers[ salaries, office salaries, office rent and sundry office expenses should ordinarily be included in the allocation. (2) Net rentals received from real estate held purely for invest- ment purposes and not used in the operation of the business are not subject to allocation but are taxable in full if the property is located in Wisconsin. Gross rentals must be reduced by all ex- penses related to such investment property. Note: Section Tax 2.41 interprets ss. 71.04 (4) and 71.25 (6), Stats. History: 1-2-56; am. Register, February, 1958, No. 26, eff. 3-1-58; am. Register, November, 1977, No. 263, eff. 12-1-77.