The federal carbon tax kicks in Monday in four provinces that refused to impose their own carbon pricing to discourage greenhouse-gas emissions.

The new tax will come into effect in Ontario, Mantioba, Saskatchewan and New Brunswick. It will affect both gas and heating fuel.

Ottawa says residents in the four provinces will be rebated their extra gasoline and home-heating costs directly through income taxes.

The tax adds 4.4 cents to the price of a litre of gasoline and about four cents to a cubic metre of natural gas.

Saskatchewan and Ontario are fighting the tax in court, and a ruling in Saskatchewan is expected in the coming months.