The congressional budget official estimates the proposed Freedom bill to temporarily double the GST reduction would cost $2.6 billion.
The government introduced a bill earlier this month to increase the six-month discount in an effort to help low- and modest-income Canadians cope with high inflation.
The proposal comes after months of pressure from the NDP to help those struggling with the rising cost of living.
Although the Conservatives first opposed the proposal, they have since indicated that they would support the bill.
The average family eligible for this discount will receive an additional $225 in January 2023.
The federal government estimates the measure will cost $2.5 billion.
This report by the Canadian Press was first published on September 29, 2022.