The opposition says households and businesses are being asked to comment on the government's carbon trading scheme, without knowing all the economic details.
Treasury modelling won't be released until October, a month after public submissions on the government's green paper close.
Shadow Treasurer Malcolm Turnbull's told ABC radio the green paper's asking people to make submissions in total ignorance of what the Treasury thinks.
Mr Turnbull says common sense dictates the Treasury's economic model and should be published before people are asked to comment.