Factbox: Carbon tax

The government has unveiled the details of the carbon tax, which will make about 500 big polluters pay an initial $23 for every tonne of carbon they put into the atmosphere.

Key elements of the carbon price package:

- Carbon price to start on July 1, 2012 starting at $23 a tonne rising at 2.5 per cent a year.

- It will be paid by around 500 biggest polluters.

- It will be replaced by an emissions trading from July 1, 2015.

- Price ceiling and floor to apply when trading starts.

- There will be two rounds of tax cuts and increases in allowances, payments and benefits.

- The tax free threshold will almost triple to $18,200 from July 1, 2012, and then increase to $19,400 from July 1, 2015.

- Every taxpayer with income below $80,000 to get tax cut from July 1, 2012.

- Costs for the average household will rise by $9.90 a week.

- Average household assistance, under the "clean energy supplement", will be $10.10 a week.

- $9.2 billion will be allocated over the first three years for industry assistance.

- Most exposed industries such as steel, aluminium, zinc, pulp and paper makers will get free permits representing 94.5 per cent of industry average carbon costs.

- $300 million has set aside help the steel industry move to a clean energy future.

- $1.3 billion has been set aside for a Coal Sector Jobs Package, targeted at mines that are most affected by the carbon price.

- A $10 billion Clean Energy Finance Corporation will be established to invest in new technology.

- $3.2 billion has been allocated to the Australian Renewable Energy Agency.

- Closure of 2000megawatts of dirtiest power generators by 2020

- Agriculture is not subject to carbon price, farmers to benefit from carbon farming.

- Small grants will be made for community-based energy efficiency programs.

- Transport fuel excluded, but heavy transport to start paying carbon tax in 2014.

- Climate Change Authority to advise on pollution caps and meeting emissions targets.