The Sustainability Council says New Zealand's bill for greenhouse gas emissions now totals $1.3 billion.
Executive director Simon Terry said New Zealand has a carbon budget deficit of 51 million tonnes, which works out to $1.3 billion.
Mr Terry says the Emissions Trading Scheme is planned to work over the long term to bring in enough income to pay New Zealand's carbon bills.
However, he says in its first five years of operation, much more money has gone out of the scheme than has come in, so the taxpayer is in a lot of debt.
The Government says the figures are mythical. Minister for International Climate Change Negotiations Tim Groser says there is no deficit and no bill taxpayers will have to pay.
Mr Groser says the only target is for the first period, and what happens in the long term will depend on a range of factors.