Iowa Admin. Code r. 701-215.21
The sales price of fuel or electricity consumed by computers, computer peripherals, machinery, or equipment that is exempt from sales and use tax under rule 701-230.14(423), 701-230.15(423), 701-230.16(423), 701-230.17(423), 701-230.19(423), or 701-230.20(423) is also exempt from sales and use tax. The sales price of electricity or other fuel consumed by replacement parts, supplies, computers, or computer peripherals used in processing or storage of data or information by an insurance company, financial institution, or commercial enterprise remains subject to tax even if such property is exempt under rules 701-230.14(423) to 701-230.20(423).
EXAMPLE: A manufacturer operates a power plant. The manufacturer uses energy from the power plant to operate machinery and equipment used directly and primarily in processing at its manufacturing facility. The fuel consumed in the manufacturer's power plant is exempt from sales and use tax.
This rule is intended to implement Iowa Code section 423.3(47)"b."
Iowa Admin. Code r. 701-215.21