Pichai used his written answers to congressional questions to disclose his company's donation to the National Review Institute, which was revealed by National Review senior editor Jonah Goldberg last year. The Google CEO confirmed the donation, stating that it was made in 2018 and would, therefore, be disclosed in the company's next report.

"Google has a long history of supporting organizations on all sides of the political spectrum," said Pichai. "Google was one of several corporate sponsors of the National Review Institute's William F. Buckley Prize Dinner in 2018, which is scheduled to be reported in our upcoming transparency report."

But the National Review Institute's website states that it received a donation from Google a year earlier, in 2017. This donation was not disclosed in Google's transparency report for that year.