Selwyn District Council has acknowledged an error in how General Rates were calculated for the 2025 26 rating year, resulting in some ratepayers being charged more than they should have been.

The council said the issue was identified in December after concerns were raised about rates revenue being higher than expected.

A review found the problem arose when updated property valuations supplied by Quotable Value were loaded into the council’s rating system. While the updated valuations correctly appeared on rates bills, the method used to calculate the General Rate component was wrong.

The council said a required safeguard in its Financial Strategy, designed to limit how much valuations could increase, was not applied.

“This means the cap that should have been applied was missed,” the council said.

As a result, some ratepayers were overcharged. Early estimates suggest the full year impact is around $85 for most residential properties and about $500 for rural properties, which generally experienced higher valuation increases.

The council said these figures were preliminary and would be confirmed through an independent review.

Mayor Lydia Gliddon said the council needed to be upfront about the mistake.

“When something isn’t right, we need to front it, fix it, and make sure it doesn’t happen again,” Gliddon said.

“Residents deserve complete confidence in how their rates are set. Bringing in an independent review is the right step to confirm facts, correct the impact and give our community assurance that every step is being taken to fix the issue and put stronger safeguards in place.”

Gliddon said no one would pay more as a result of the correction.

“Affected ratepayers will receive a credit or a reduced instalment in Quarter 4,” she said.

Interim Chief Executive Steve Gibling said the council took the issue seriously and moved quickly once it was identified.

“Our team takes this matter extremely seriously. We acted quickly once the issue was identified and have brought in external experts to ensure every calculation is validated,” Gibling said.

“We will communicate openly with residents as the work progresses and make sure any necessary corrections are made promptly and accurately.”

The council has engaged an external party to independently check the calculations. That review will confirm exactly which properties were affected, how much they were overcharged, and how the issue will be remedied through refunds or adjustments.

The independent review is already underway.

The council said Quarter 3 rates invoices, which are being issued from this week, will remain unchanged. Any corrections will be applied in Quarter 4, meaning most affected ratepayers should see a reduction in their final instalment.

Gliddon said she understood the frustration residents would feel.

“On behalf of council, I apologise for this error,” she said.

“I remain committed to ensuring our rating system is fair, accurate, and transparent for all Selwyn residents.”

Selwyn District Council said it was committed to restoring confidence in the rating system and ensuring the error was not repeated.