Assistant Treasurer Daniel Mulino has rejected criticism that Labor’s move to double the tax on high balance superannuation accounts will kill aspiration, saying the number of people affected would grow slowly over time and the $3 million threshold was more than enough for a dignified retirement.

In his first extended interview since being appointed to the ministry after the May 3 federal election, Mulino also did not rule out making further changes to Australia’s $4.2 trillion superannuation system.