The Canadian New Democratic Party (NDP) has devoted much of its energy in recent months to opposing the implementation of the Harmonized Sales Tax (HST) in Ontario and British Columbia. The new taxes came into effect on July 1, 2010. The HST merges the Goods and Services Tax (GST) with the Provincial Sales Tax (PST) in both provinces. Items covered by the GST that were previously exempt from the PST are included under the new HST.

Much of the Canadian left has been supportive of the anti-HST campaign on the grounds that consumption taxes are regressive (i.e. people pay the same rate of tax regardless of income).