Idaho Administrative Code
Title IDAPA 35 - Tax Commission, State
Rule 35.01.01 - INCOME TAX ADMINISTRATIVE RULES
Section 35.01.01.350 - PRORATION OF DEDUCTIONS

01. In General. In most cases a taxpayer's allowable deduction applies only to the apportionable income arising from a particular trade or business or to a particular item of nonapportionable income. In some cases an allowable deduction applies to the apportionable income of more than one trade or business, to several items of nonapportionable income, or to both. In these cases the deduction is to be prorated among the trades or businesses and the items of nonapportionable income in a manner that fairly distributes the deduction among the classes of income to which it applies.

02. Year to Year Consistency. If a taxpayer departs from or modifies the method used for prorating any deduction in prior year Idaho returns, the taxpayer is to disclose the nature and extent of all modifications in its current year return.

03. State to State Consistency. If the returns or reports filed by a taxpayer with all states to which the taxpayer reports pursuant to Section 63-3027, Idaho Code; Article IV of the Multistate Tax Compact; or the Uniform Division of Income for Tax Purposes Act are not uniform in applying or prorating any deduction, the taxpayer is to disclose the nature and extent of the variance in its current year Idaho return.