Labour’s manifesto had not at this stage been published. There was, nevertheless, no reason to believe Jeremy Corbyn would raise corporation tax to the highest in Europe. As Channel 4’s Fact Check noted: “Labour say they will raise the main rate of corporation tax to 26 per cent by 2022 — the level it was in 2011.” This would not be the highest in Europe. In France corporation tax starts at 31 percent, and in Belgium the rate is 29 percent.
(When the manifesto was published, after Johnson made his comments, Labour committed to raising corporation tax to 26 percent.)
Boris Johnson had no basis in fact for his false claim.