Manukau Mayor and Super City mayoral front-runner Len Brown broke nearly every rule in the book when he put $810 on his council credit card for a dinner at a Manurewa restaurant last September.
The council credit card policy bars card-holders from submitting only an eftpos receipt to verify spending, but that is all Mr Brown provided after the dinner at Volare Restaurant.
He also breached rules requiring him to explain the purpose of the dinner, list who was present, provide an itemised breakdown of the dinner, a GST receipt and a tax invoice.
Finance director Dave Foster, who is responsible for monitoring Mr Brown's credit card use approved the expenditure on the basis of an eftpos receipt.
It was not until May 31 this year - after Mr Brown's credit card spending became public - that Audit New Zealand told the council tax invoices were missing on some credit card transactions.
Council staff have identified 25 instances, some linked to Mr Brown, in which tax invoices are missing.
The council has asked for tax invoices from several suppliers, including Volare Restaurant.
Mr Brown's credit card problems will come under the microscope today when documents detailing $16,977.22 of his credit card expenditure since 2007 will be discussed by the council's policy and activities committee.
The first-term mayor, who shot to an 11.4 percentage point lead over Auckland City Mayor John Banks in a Herald-DigiPoll survey of Super City mayoral popularity, has admitted making four personal purchases on his council credit card totalling $638.27.
Last night, he was defensive about his dinner at Volare Restaurant.
"This is a job that requires my attention six or seven days a week and I have done my very best with regard to abiding by the rules and regulations as prescribed by our policy.
"I think generally my expenditure has been low, has been in the ambit of what is expected of the mayor of a city of 370,000 people," Mr Brown said.
He acknowledged giving only an eftpos receipt for the dinner, but said a proper receipt was later provided.
Asked why he had not provided an itemised receipt, Mr Brown said: "I don't know. It is some time back. The council officers followed that up through the course of their audit trail to ensure satisfaction."
Cabinet ministers' official credit card records, made public last week, include fully itemised receipts and some details of who they were entertaining.
Mr Brown cut up his credit card on Campbell Live last week and told the Herald that if he became the first mayor of the Super City, he would use a purchase account and regularly publish details of his spending.
He said he accepted the public scrutiny, but believed it was part of a smear campaign by his opponents because of his poll lead over Mr Banks.