It is not a tax
They are carbon credits that corporations can buy on a "carbon stock market" in order to have the right to release CO2 in the air. If they pollute less than the carbon credit that they hold, then they can resell the credits to other corporations for a profit. If they pollute more then they need to buy credits from other corporations.
The provincial governments sell those credits in exchange for money that they use for general spending. Quebec just sold $171 million in carbon credits.
The ideas behind this
Capping carbon credits means that the government can decide how much carbon is released in the air each year and corporations that fail by releasing more than the credit they bought can be fined.
The revenues from the carbon credits enables the governments to shift the burden of paying for some government services from the taxpayers towards corporations.
All in all
The Carbon credit market should basically be financially neutral for the consumers. As the corporations will pass the cost of the carbon credit market down to its customers, the extra revenues for the government will make it possible to avoid any tax hikes and maybe even allow for some tax relief without cutting services.
Extra benefit
Consumers eager to avoid paying for the carbon credit scheme will buy products manufactured by corporations that produce less carbon emissions. These corporations will be able to sell their good for less than their heavy carbon competitors. This will motivate businesses to reduce their carbon emissions and help slow down the greenhouse problem.
Conclusion
Savvy shoppers will be reduce and sometimes avoid the impact on retail prices of the carbon credit market by buying products that are made while producing less or no carbon emissions.
The environment will win because people will buy more environmentally friendly products.
The taxpayers will win by letting their governments seek revenues outside income and sales taxes, which means less tax hikes or less service cuts.
The corporations will win by innovating and using less carbon intensive production methods and by selling their extra carbon credits to their less efficient competitors for a profit.
Humankind will win by living in a more hospitable environment.
What's not to like?