Iowa Admin. Code r. 701-282.3
Tangible personal property purchased outside the state and consumed in creating power, heat or steam for processing tangible personal property or for generating electric current intended to be sold ultimately at retail is exempt from sales and use tax. If the property purchased to be consumed as fuel in creating power, heat or steam for processing is also used in the heating of the factory or office, ventilation of the building, lighting of the premises or for any use other than that of direct processing, that portion of the property so used is subject to use tax.
When buying tangible personal property, part of which is exempt as fuel under the provisions of the law, from an out-of-state seller registered to collect tax for the state, the purchaser shall furnish to such registered seller a written certificate certifying the cost of the property that is to be used for processing and is, therefore, exempt. The certificate shall also show the cost of the property that is not to be used in processing and is, therefore, taxable in order that the registered seller may properly bill the amount of use tax due.
This rule is intended to implement Iowa Code section 423.6(3)"b."
Iowa Admin. Code r. 701-282.3