In November last year Ms Jenkins wrote to 120 chief executives across the country, requesting they release statements allowing employees and former employees who had signed non-disclosure agreements about sexual harassment issues to give evidence without an application process.

Only 18 employers have signed up, including ANZ, Australian National University, Rio Tinto, and the Commonwealth Bank.

Public servants in NSW and Queensland are covered by waivers that allow them to give evidence without first having to seek permission from the relevant agency or another public service body.

It's not clear whether the Secretaries Board, which is led by Prime Minister and Cabinet secretary Martin Parkinson and includes the 18 departmental secretaries and Public Service Commissioner Peter Woolcott, consulted with the Sex Discrimination Commissioner on their plan.

"I asked employers to issue a limited waiver to allow people to make confidential submissions to the National Inquiry," Ms Jenkins said.

"Some employers contacted us with questions and, when they did, we answered them. Those who have agreed to the waiver are listed on our website."

The ability to give evidence despite having previously signed a non-disclosure agreement was important in the lead up to the banking royal commission, and Ms Jenkins said the importance of waivers without an application process had added importance when it came to harassment victims.

"The ability to make a confidential submission is paramount to the integrity of our consultation process. Requiring individuals to seek consent potentially jeopardises that confidentiality, and may risk retrauma of victims of sexual harassment," she said.

While the 18 employers who have agreed to offer limited waivers to their employees are listed on the website for the inquiry, the federal public service is not among them.

"The APSC and federal government departments did not agree to the waiver proposed by the Commission and are therefore not listed on the AHRC website. However, where current or former APS employees make inquiries to us we are directing them to the APSC statement," Ms Jenkins said.

The national inquiry into workplace sexual harassment was launched in June last year, after a survey by the Australian Human Rights Commission found 23 per cent of women had experienced some form of workplace sexual harassment within the prior 12 months.

Almost 40 per cent of women had experienced sexual harassment at work in the prior five years.

A survey of female members of the Community and Public Sector Union conducted for International Women's Day last year found 3.6 per cent of women reported having experienced sexual harassment in the prior 12 months, indicating rates of sexual harassment may be lower in the public service.

The deadline for submissions to the inquiry was extended in December in order to give more time for people who had signed non-disclosure agreements to contribute. Submissions now close on February 28.

A spokesman for the Department of Prime Minister and Cabinet said secretaries agreed to a consistent approach after a request from the Sex Discrimination Commissioner.

"The approach adopted by the Secretaries Board provides an avenue for APS employees and former APS employees to contribute confidentially in support of the national inquiry," the spokesman said.

"The agreed approach ensures affected employees do not have to deal directly with the agency they entered into a non-disclosure agreement with, and allows the APSC to act as a conduit between the employee and the agency."

The spokesman said the process balanced the need for the agencies to manage legal risks to all parties in individual cases, and the public service commission would "conduct the process sympathetically and in strict confidence".