Ind. Code § 6-5.5-1-20
As used in this article, "bonus depreciation" means an amount equal to that part of any depreciation allowance allowed in computing the taxpayer's federal taxable income that is attributable to the additional first-year special depreciation allowance (bonus depreciation) for qualified property allowed under Section 168(k) of the Internal Revenue Code, including the special depreciation allowance for 50-percent bonus depreciation property. For taxable years beginning after December 31, 2017, the term does not include any amount of additional first-year special depreciation allowance under Section 168(k) of the Internal Revenue Code in the amount of adjusted gross income realized on the exchange of property that otherwise would have been deferred under Section 1031 of the Internal Revenue Code in effect on January 1, 2017, if:
For purposes of this section, if the taxpayer elected to claim a deduction under Section 179 of the Internal Revenue Code with regard to an item of acquired property, the adjusted gross income realized on the exchange must be reduced (but not below zero dollars ($0)) by the amount of the deduction under Section 179 of the Internal Revenue Code elected to be claimed on the acquired property.
IC 6-5.5-1-20