(b) Applicable percentage. -- For the purposes of subsection (a) of this section, the applicable percentage for any property is determined under the following table:

If useful life is: The applicable percentage is:

4 years or more but less than 6 years 33 1/3

6 years or more but less than 8 years 66 2/3

8 years or more 100

The useful life of any property for purposes of this section is determined pursuant to the methods as the Tax Commissioner may require as of the date the property is first placed in service or use in this state by the taxpayer, determined as the Tax Commissioner may require.

(c) Placed in service or use. -- For purposes of the credit allowed by this article, property is considered placed in service or use in the earlier of the following taxable years:

1. (1) The taxable year in which, under the taxpayer's depreciation practice, the period for depreciation with respect to the property begins; or
2. (2) The taxable year in which the property is placed in a condition or state of readiness and availability for a specifically assigned function.

(d) Cost. -- For purposes of this section, the cost of property purchased for manufacturing investment, is determined under the following rules:

1. (1) Trade-ins. -- Cost will not include the value of property given in trade or exchange for property purchased for manufacturing investment;
2. (2) Damaged, destroyed or stolen property. -- If property is damaged or destroyed by fire, flood, storm or other casualty, or is stolen, then the cost of replacement property will not include any insurance proceeds received in compensation for the loss;
3. (3) Rental property. -– The cost of property acquired by lease for a term of ten years or longer is one hundred percent of the rent reserved for the primary term of the lease, not to exceed twenty years;
4. (4) Property purchased for multiple use. -- The cost of property purchased for multiple business use including use as a component part of a new or expanded or revitalized industrial facility, together with some other business or activity not eligible for credit under this article, is apportioned between the businesses and occupations. The amount apportioned to the new or expanded or revitalized industrial facility is considered as a qualified investment, subject to the conditions and limitations of this section; and
5. (5) Self-constructed property. -- In the case of self-constructed property, the cost thereof shall be the amount properly charged to the capital account for purposes of depreciation.