Deputy President Kgalema Motlanthe on Thursday provided some insight into how the South African Revenue Service (Sars) conducted so-called "lifestyle audits".

Responding to questions in the National Council of Provinces on Thursday, he also repeated that government was not considering lifestyle audits for ministers, deputy ministers, and senior public servants as "there are already appropriate measures in place".

Ministers and deputy ministers were required in terms of the Code of Ethics for Members of Parliament and the Executive Members' Ethics Act and Code to disclose details of their financial interests, assets, and gifts received.

Senior public servants from the level of director upwards were required to do the same in terms of the public service regulations.

"As I am sure that you aware, violations of the Parliamentary code are handled by Parliament and have been dealt with effectively in the past.

"Complaints against violations of the Executive Ethics Code can also be dealt with by the Public Protector," he said.

Sars conducted investigations of people who appeared to be living beyond their means.

These investigations started on the basis of information obtained from various sources, including the Sars anti-corruption and fraud hotline, income tax returns a taxpayer submitted to Sars, and suspicious activity reports from members of the public.

A lifestyle questionnaire was one method of obtaining information from a taxpayer and, together with other information sources, helped Sars in matching the lifestyle trends, income streams, and the asset-base of a taxpayer to what had been declared in an income tax return.

"The accumulated wealth has to be explained by the taxpayer for tax purposes. Any unexplained wealth is taxed," he said.

The compliance and risk unit within Sars conducted the risk analysis of taxpayer information.

If there was a mismatch between what the taxpayer had declared and what Sars had found, the case was referred for an audit.

If it was confirmed that the taxpayer had evaded tax, penalties were levied, interest charged, and additional tax of up to 200% of the evaded tax was charged.

Depending on the circumstances, the case could then be handed to Sars criminal investigation who then engaged the South African Police Service and a specialised tax unit for criminal prosecution within the National Prosecuting Authority.

More than 10 000 such audits had been conducted by Sars over the past two years, Motlanthe said.

The Prevention and Combating of Corrupt Activities Act also provided for an investigation into a person who appeared to own property disproportionate to their income.