The federal government is also tightening eligibility requirements for employer-sponsored permanent skilled visas. This includes that applicants must be aged 45 or under at the time of application.

Accounting and legal firms and recruitment agencies are worried that an age limit will make it harder to attract skilled CEOs and other high-level executives.

"Talent comes in all shapes and sizes and doesn't have a cut-off date," said Juliet Bourke, consulting partner and co-leader of the Deloitte human capital practice.

"In an environment of healthy ageing, and societal encouragement to work until at least 70 years of age, it will be disappointing if businesses cannot tap into global talent aged over 45 years."

Often skilled workers who initially come on 457 visas, after two years with their nominating employer, can apply for permanent residency under the employer-sponsored permanent skilled visas (subclass 186).

Kristopher Kunasingam, lawyer/migration consultant with Hall & Wilcox Lawyers, said most permanent residency applicants they act for are in the 45-50-year-old age bracket.

"By limiting the age to 45 the changes will limit the talent and experience available to Australian corporates," he said.

"We expect to see an impact on the level of talent available on foreign work visas for general managers, chief executives and senior strategy people."

The age restriction for this visa class could also make local hires more expensive .

Charles Cameron, chief executive of the Recruitment & Consulting Services Association (RCSA), an industry body for the recruitment and employment services sector in Australia and New Zealand, says his members have told him that the CEO search will become harder and "could increase the cost of local talent".

One of the RCSA's members is TRANSEARCH Australia, a global search firm that sources about 80 per cent of talent at the CEO level. "Their assessment is it will affect the senior executive market," Mr Cameron said.

The greatest impact, he said, would be in education and healthcare sectors where people often needed to have greater technical skills and at least 20 to 25 years of experience.

Nicole Gorton, director of recruitment agency Robert Half for the APAC region, said searches for CEOs were often global. "Any age restriction for skilled foreign workers may limit the scope of executive recruitment," Ms Gorton said.

"It is very common to have international professionals at the C-suite level in Australian companies as the available local talent market can be limited, making it sometimes necessary to recruit from overseas.

"The changes might hold the risk that businesses will be further challenged sourcing skilled talent in several areas, leaving them uncertain about their near-future growth prospects."

In addition, Turnbull's plan to abolish 457 visas and restrict skilled foreign talent would "decrease the supply of highly specialised professionals in several functional areas, particularly within the technology sector".

"The IT industry is the biggest sponsor of 457 workers, and with the supply of specialised Australian IT candidates not meeting demand in many functional areas, businesses are left with critical skills gaps for which they have relied extensively on foreign-skilled talent," she said.

"With the proposed changes where - according to the proposed occupation list - several IT jobs would be removed from the list, the talent gap is expected to increase."

Katherine Woodthorpe, chairwoman of Sydney and Brisbane startup co-working space Fishburners, said: "The age limit of 45 raises a potential problem for specialist industries such as tech, where Australians with sufficient and suitable international C-Suite experience can be thin on the ground."

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