The court will hear the case on March 13.

It is understood that Tang's wife, Lisa Kuo Yu-chin, was charged in her capacity as "the owner's agent" while Tang himself will escape any charges.

Architect Henry Ho Chung-yi, along with registered structural engineer Wong Pak-lam and a registered contractor were also charged. The department said the prosecution involved two charges.

One was related to building works being carried out without the approval and consent of the Buildings Authority.

That has a maximum penalty of two years' imprisonment and a fine of HK$400,000.

The second charge concerned knowingly "misrepresenting a material fact in documents presented to the authority", which could result in a jail term of up to three years and a maximum fine of HK$1 million.

The Buildings Department investigation report and evidence - including witness statements and test results - were passed to the Department of Justice, which decided to press ahead with the charges.

Secretary for Development Paul Chan Mo-po would not confirm yesterday whether Kuo had been charged.

A spokesman for Tang said they had received a letter from the Buildings Department and the matter was being handled by their lawyers.

"No comment will be made since the case is now in legal proceedings," the spokesman said.

The couple were out of town yesterday.

Wong, the structural engineer, has also referred the case to his lawyer and would not make further comment.

The investigation has only just been completed - a year after the luxurious basement, complete with skylights, was revealed by local media in the final weeks of last year's chief executive election campaign.

Negative publicity over the illegal basement was then compounded by Tang's handling of the scandal. While he co-owned the house with his wife until 2010, he said he was not responsible for breaking the law.

The scandal was a huge blow to Tang's campaign and his popularity rating slumped to less than 15 per cent, effectively ending any hope of him becoming chief executive.

It was also seized upon by his election rival Leung Chun-ying.

But after Leung won the poll, illegal works - including a much smaller basement - were also found at his home in June.

Last month, Tang openly questioned whether the government was dealing with the matter fairly. He said his lawyers and architects had commented that they had never before seen such an in-depth probe into illegal structures.

Asked what effect the prosecutions would have on its ongoing investigation into Tang, the Independent Commission Against Corruption said it would not comment on individual cases.

How The Scandal Unfolded

: Henry Tang Ying-yen admits having illegal structures at 7 York Road, Kowloon Tong - a house he co-owned with his wife, Lisa Kuo Yu-chin, until 2010. He apologises on a radio programme after Chinese-language newspaper reported there was an excavated area connected to the base of a swimming pool.

: The Buildings Department says in a mandatory removal order for the breaches that the property owner listed in the Land Registry - Tang's wife - would be held responsible under the law.

: The Buildings Department confirms the existence of the 2,250 sq ft basement, which was not shown in the approved building plans.

: The Buildings Department says it has started an investigation in response to media reports that suggested the basement existed before an occupation permit was issued in 2007. Tang says the basement was built after the permit was issued, essentially dismissing reports he had concealed the basement project from inspectors. All the parties involved - including the architect, structural engineers, contractors and Kuo - are invited to provide information for the investigation.

: Tang formally signs up for the chief executive race.

: The then secretary for development, Carrie Lam Cheng Yuet-ngor, says the Buildings Department has compiled a list of 40 people to interview about work done at Tang's Kowloon Tong home.

: Tang loses the election to Leung Chun-ying, a loss attributed largely to the illegal basement and his earlier admission of infidelity.

: Tang says illegal structures at his property are the subject of a probe by the Independent Commission Against Corruption.

: Tang says it was unfair and laughable for Leung to have attacked him over the illegal basement when Leung also had unauthorised installations at his properties.