The number of contractors and labour hire staff working in and with government agencies remains largely hidden from view, as it has done for years.

Every now and then, glimpses emerge of that population of outsourced workers, but only in its parts. In 2018, off the back of an inquiry from ACT-based Labor MP David Smith, an explosion of outsourcing at the Defence Department was revealed in figures showing 32,000 non-public servants received government security clearances in two years.

The government's AusTender website shows contracts issued for temporary workers in 2020 reached $1.35 billion across the public sector, an increase of about $500 million compared to the previous year.

Documents released under freedom of information laws last year showed the Defence Department's outsourced civilian workforce numbered about 29,000 - far larger than its internal contingent of 17,000 public servants.

One of the clearest pictures of contractor numbers yet emerged in a Canberra Times analysis of figures from departments last month. It found about one in five people working in federal government departments are employed on external contracts or through labour-hire firms. That figure aligns with the estimates of the main union for public servants, the Community and Public Sector Union.

In the Department of Veterans' Affairs, contractors nearly outnumber public servants. More than 40 per cent of the Department of Veterans' Affairs workforce are contractors or labour hire, a figure the agency says reflects fluctuations of its service delivery. At the Attorney-General's Department, 21 per cent of workers are contractors.

It's helpful to see the contractor and labour hire workforce of the public service in its parts, but it's past time the government revealed its entirety.

The Thodey review of the federal bureaucracy found that in the four years to 2016-17, government spending on labour contractors soared, more than doubling to reach $738 million a year.

That growing spend is a direct result of the Coalition's cap on public service staffing. The government says the main reason for the restriction is to save money. If frugality and efficiency are actually the motives for the staffing cap, then the government should understand the results of its spending on outsourcing. That includes knowing the size of its outsourced workforce, to a person. What's more, it should reveal this to the public.

There are more than enough indicators that the size of the outsourced public service workforce is large and growing. These employees are doing the work of government, so it's the public's business to know how many they number, where they work in the public service, and what they do. It's past the point where the government needs to measure and account for this.

To put it simply, too much of the bureaucracy's workforce is hidden from view for the public to understand its government, and hold it accountable. Lift the veil.

An obvious place to find out the true size of the outsourced public service workforce would be to count contractors and labour hire staff in the Australian Public Service's annual census of public servants, and include them in statistics about the federal bureaucracy.

The CPSU is already doing its own census of labour hire staff, and may come to know more about these workers than the government ultimately paying them.

The Defence Department counts its external workforce. It's a feasible task for every agency to do the same, and for the public service commission to collect and publish that information.