The Supreme Court has turned down Trustpower's appeal to claim tax deductions on $17.7 million of project costs.
The country's top court sided with the Inland Revenue Department, disallowing Trustpower's appeal to claim tax deductions for the cost of what it described as "feasibility expenditure" on four potential projects in the South Island.
"The expression 'feasibility expenditure' does not fully capture the significance of resource consents and thus the costs incurred in obtaining them," the judgment, delivered by Justice William Young, said.
"Securing the consents amounted to tangible progress towards eventual completion of the projects (which could not be built without them)."
Trustpower was seeking to overturn a Court of Appeal ruling disallowing the deductions in the 2006, 2007 and 2008 tax years.
Trading in the NZX-listed shares was halted pending the release of the judgment. The shares last traded at $8.20.