It is not known what, or whom, the complaint is about.

Under new procedures, each council's complaints co-ordinator must, within three months of the end of September each year, report on complaints against councillors and the general manager.

The report will then be presented to the council and the Division of Local Government.

Shellharbour's code of conduct report showed just one complaint was made but $6362 was spent on that complaint, which had been investigated only by the conduct reviewer.

It has yet to be investigated by a conduct review committee.

Neighbouring Kiama Council investigated one complaint, which cost the council $400 and was resolved before it could be referred to a conduct reviewer.

Councillor Kellie Marsh asked why it cost $6000 for one person to investigate one complaint. She asked at what stage, if any, the costs were capped, where the money came from and how long the process should take.

General manager Michael Willis said the one thing that could be drawn from the report was "the matter is yet to be concluded".

"I am not at liberty to go into any discussions about it," he said.

Shellharbour Mayor Marianne Saliba said the general manager could not say how much the investigation would cost because it was an ongoing process that had to be followed.

"What the costs will be depends on the process it goes through and how long it takes, and that is not something any of us or the general manager can answer," she said.

Deputy mayor Paul Rankin said the council had done well to have only one complaint.

"I know that one council up north had 38," he said.

Shoalhaven City Council recently revealed it spent more than $37,000 investigating code of conduct complaints against councillors in the 12 months to August 31.