The National Post reports in its Wednesday edition that Canada's promised digital services tax targeting the world's biggest tech and social media giants will bring in double the amount of revenue as previously estimated, according to the Parliamentary Budget Officer. The Post's Anja Karadeglija writes that in a report released Tuesday, the PBO said the tax would "increase federal government revenues" by $7.2-billion over five years. Previous estimates put that number at $3.4-billion. The United States has warned of retaliation if Canada goes ahead with the digital services tax before an OECD deal is in place. The digital services tax was first promised in the 2021 budget and would be retroactive to Jan. 1, 2022. It targets large companies that operate on-line marketplaces, social media platforms and earn revenue from on-line advertising, such as Amazon, Google, Facebook, Uber and Airbnb. The 3-per-cent tax on digital services revenues over $20-million would apply to companies with global revenues of more than about $1.08-billion. On Monday, Treasury Secretary Janet Yellen said the U.S. will not be ready to sign the OECD deal on time, a move that could trigger other countries to introduce their own unilateral taxes.