A woman who was sent an invoice five years late has been left wondering what else is gathering dust in the council's billing system.
Whangarei's Julie Wills thought it was odd to receive a bill in May for a swimming pool inspection she had no idea had been done.
When she contacted Whangarei District Council about it, she was told it was actually a bill from 2011 which had never been sent.
"It's pretty concerning there's that kind of inefficiency going on, if it's common," Ms Wills said. "If a private business was sending out accounts five years late they wouldn't survive long."
Ms Wills said she would pay the $132 bill, which she suspected was leftover from the building consent process for the pool. The tax invoice was dated September 29, 2011.
"The actual money is no big deal, if it had come with an explanation and an apology," Ms Wills said.
She had raised her situation in the media as she felt the council needed to be questioned over how frequently similar things were happening.
A spokeswoman for the district council said staff were concerned and were investigating the incident. The council planned to contact Ms Wills next week.