2019 report: Accuracy and completeness of the 2018 electoral registers in Great Britain


We run accuracy and completeness studies to measure the quality of the electoral registers, and assess how this changes in response to legislative developments and administrative and population changes.

The results for Great Britain in December 2018 show that:

  • Parliamentary registers were 85% complete and 89% accurate
  • Local government registers were 83% complete and 89% accurate

The findings lead to two main estimates:

  • between 8.3 and 9.4 million people in Great Britain who were eligible to be on the local government registers were not correctly registered
  • there were between 4.7 and 5.6 million inaccurate entries on the local government registers

Chart titled 'Accuracy and Completeness of the December 2018 registers in Great Britain'. Chart shows that completeness for local government registers was 83% and 84% for parliamentary registers. Accuracy was 89% for both local government and parliamentary registers.

This is our first study since the 2015 assessment of the registers, following the transition to Individual Electoral Registration (IER). Since 2015 the levels of completeness have stayed at around the same level, with a not statistically significant decline of around 1 percentage point on the local government registers, while the accuracy has fallen by two percentage points.

Age and mobility

Our research confirms that age and mobility continue to be the strongest variables associated with lower levels of completeness. Plans to reform the annual canvass starting in 2020 are an important first step, enabling Electoral Registration Officers (EROs) to focus resources on households that have changed composition.

Modernising electoral registration

However, there is more that could and should be done to modernise registration processes in Great Britain to provide the best opportunity for ensuring that as many people as possible are correctly registered.

Earlier this year we published the findings from a series of feasibility studies exploring how reforms, including automatic or more automated registration, could be delivered. The studies found that these changes are feasible from a technical and operational perspective and could be implemented without radically altering the structure of the electoral registration system in the UK.

What we mean by accuracy and completeness

The quality of the electoral registers is measured in two main ways: their accuracy and their completeness.

By accuracy we mean that ‘there are no false entries on the electoral registers’. It is the measure of the percentage of entries on the registers which relate to verified and eligible voters who are resident at that address. Inaccurate register entries may relate to entries which have become redundant (for example, due to home movement), which are ineligible and have been included unintentionally, or which are fraudulent.

By completeness, we mean that ‘every person who is entitled to have an entry on an electoral register is registered’. It refers to the percentage of eligible people who are registered at their current address. The proportion of eligible people who are not included on the register at their current address constitutes the rate of under-registration.