The third rebranding of NBN Co is expected to cost close to $1 million and an additional $4.5 million will be spent on regional television advertising.

The costings were revealed by Communications Minister Malcolm Turnbull after being asked by Queensland senator Joe Ludwig to detail spending during a Senate estimates hearing.

The third rebranding of NBN Co was launched in April in an effort to "create a sense of optimism and inspiration and encourage people to harness their potential".

When the company was launched in April 2009, it was called the National Broadband Network Company, before changing to NBN Co Ltd seven months later, and then to NBN Co.

NBN Co general manager of brand and insights Kent Heffernan said the latest rebranding would represent value for money and make the project more viable.