Question to the Cabinet Office:

To ask the Minister for the Cabinet Office, what recent estimate his Department has made of the number of adults not registered to vote in each year from 2010 to date.

Data concerning the number people registered to vote is held by Electoral Registration Officers, not by the Government. Each year, figures relating to the 1 December published register are provided by Electoral Registration Officers to the Office for National Statistics. After processing, the ONS then publishes the collected statistics on its website. You can find these at goo.gl/uXB4aK. Statistics relating to the 1 December 2017 register will be available in 2018.