Broad changes to tighten the eligibility criteria for presidential candidates from the public and private sectors have been recommended by the Constitutional Commission.

The changes are to ensure that whoever is elected has the expertise and experience to carry out the president's duties as guardian of the national reserves, which will involve complex and highly technical issues, the commission said in its report made public yesterday.

The commission, chaired by Chief Justice Sundaresh Menon, was appointed by Prime Minister Lee Hsien Loong in February to review the institution of the elected presidency. It submitted its report to Mr Lee last month.

One key proposal is that potential candidates must have served six years in a public or private sector position which qualifies them to stand for election. This is double the current requirement of three years.

To ensure that a candidate's experience is current, the commission recommended that the entire period of the candidate's qualifying tenure must be within 15 years before the nomination day of the presidential election.

This means if the presidential election takes place in August next year, a potential candidate must have held his qualifying position for at least six years since 2002.

Another significant proposed change is to the current criterion that a candidate must have had experience running large, complex companies that have a paid-up capital of $100 million.

The commission suggests revising the amount to $500 million in shareholders' equity, as it is a better indicator of a company's size and complexity. "Unlike paid-up capital, shareholders' equity reflects the company's current (and not just its historical) recorded worth," the report explained.

The $500 million figure was derived after considering the magnitude of the decisions that a president may have to make, and the confidence he must have in making decisions involving very large sums of money, including from the reserves.

The $500 million figure should also be reviewed periodically. This could be done a year before every alternate presidential election, the commission proposed.

"Quantitative thresholds cannot remain fixed in perpetuity for the self-evident reason that the economic situation in a country, or, for that matter, even the value of money in real terms, does not remain static," the report said.

The commission also said that only the person holding the most senior executive position who "bears the ultimate weight of responsibility for the fate of a company" should be eligible. Current rules allow the chairman or chief executive of a qualifying company to stand.

But this places "undue emphasis on form rather than substance", the commission said, noting that a non-executive chairman not actively running a company would not have the necessary expertise.

The commission also proposed a profitability requirement to show that a potential candidate performed acceptably while helming a company. The firm should have recorded a net profit during the candidate's time heading it. The company must also not go into liquidation or insolvency within three years of the candidate's departure.

The commission said public sector candidates should not be subject to a similar performance assessment, as it is harder to measure the performance of a public sector entity whose task is to advance the public interest and whose policies may bear fruit only in the long run.

But the commission said its proposal to double the duration which applicants must have served in the qualifying office will be an "indirect indication" of performance for public sector candidates, as it will "filter out those who were either removed or not reappointed because they had been found wanting".

Key public service appointment holders who qualify include ministers, the Chief Justice, Speaker of Parliament, Attorney-General and permanent secretaries.

The commission said the Accountant-General and Auditor-General should be removed from the list for automatic qualification as they do not deal with the pressures of government decision-making, and "play an indispensable but ultimately ancillary (and comparatively narrow) role" in public service.

The commission also noted that it received feedback that raising the eligibility criteria will shrink the pool of potential candidates.

But it said that "an undue focus on the size of the pool is a distraction from the real task at hand, which is to ensure that candidates possess the requisite qualifications to satisfactorily discharge the responsibilities of the office".