The Abbott government has begun laying the groundwork for a $4 billion privatisation of Medibank Private without having received expert advice on whether the health insurer should be sold off.

Finance Minister Mathias Cormann has repeatedly said that no decision has been made on the timing or structure of a sale - the biggest privatisation since the float of rail company QR National.

But Fairfax Media has learnt that a fortnight ago a team of corporate spin doctors began drawing up plans to sell the idea for a full or partial-privatisation to the public.

The company, Newgate Communications, whose 10 senior executives include four former Liberal government staffers, is being paid $2000 a day to devise a communications strategy. The contract, worth $211,000 over five months, runs until June 30.

It was awarded by the Department of Finance on January 29, a month before Mr Cormann is due to receive the results of the scoping study that was supposed to be the trigger for a sale.

In November, Mr Cormann appointed investment bank Lazard to do the scoping study. It has until the end of February to advise on the readiness of Medibank for privatisation, as well as recommend a method of sale, timing and estimated proceeds.

In announcing the appointment of Lazard, Mr Cormann stressed: ''The government has not made any decisions yet regarding the timing and structure of any sale."

But the appointment of Newgate has been taken as a clear signal that Medibank will be put on the block in time for the proceeds to be factored into Treasurer Joe Hockey's first budget in May.

Mr Cormann's office said Newgate will provide communications advice on any announcements flowing from the findings of the scoping study. The contract contained the option of retaining the company for the entire sale process, which could drag into 2015.

Lazard will advise whether a full float on the Australian Stock Exchange, a partial float or a so-called ''trade sale'' to another health insurance provider will maximise value for the taxpayer. Medibank, which returned a profit to government of $315 million in 2013, is valued at about $4 billion by analysts.

Labor claims the government has already decided to sell Medibank without waiting for advice or demonstrating how it would increase competition or put downward pressure on health insurance premiums.

"$2000 a day to spin to Australians why assets should be privatised is simply the most extraordinary government waste,'' said shadow health spokeswoman Catherine King. "[The government] will pay $2000 a day for a spin doctor, but they won't support Toyota jobs.''