How the electoral register works and why millions are missing

The electoral register is not one national list but hundreds of local ones, each maintained by an Electoral Registration Officer, a council official in England and Wales, a joint-board appointee in much of Scotland, and a single Chief Electoral Officer for the whole of Northern Ireland. Getting onto it is the precondition for everything else in a British election: no entry, no ballot paper, however eligible you are in principle.

Until 2014, registration in Great Britain worked by household. One person, traditionally the "head of household", filled in a form listing everyone eligible at the address, and the whole house went on the register in a single stroke. The Electoral Registration and Administration Act 2013 replaced that with individual electoral registration, under which each person applies separately, supplying a National Insurance number and date of birth that are matched against Department for Work and Pensions records before the entry is confirmed. Northern Ireland had made the same move back in 2002, after concerns about fraudulent entries, and the mainland reform was sold on the same prospectus: a register of verified individuals rather than names vouched for by whoever opened the post.

On its own terms, the change worked. Duplicate and phantom entries became far harder to create, and the online application at GOV.UK, live since 2014, takes a few minutes and drives enormous surges before big polls, with millions of applications in the weeks before a general election. But the fraud fix carried a completeness cost. Under the household system, one motivated person captured a whole flatshare; under individual registration, every tenant, lodger and adult child has to act for themselves, and many never do. The Electoral Commission's accuracy and completeness studies have repeatedly put the number of people in Great Britain who are missing from the register, or recorded at an old address, at around eight million. Completeness for owner-occupiers sits comfortably above ninety per cent; for private renters it falls towards sixty, and registration among under-35s trails the retired by a wide margin. The strongest single predictor of being missing is having moved recently, which is why the gap maps so tightly onto renting and youth.

The maintenance machinery leans against this, but only partially. Each autumn the annual canvass requires EROs to check every household; since a 2020 reform, existing entries are first data-matched against DWP records, so stable households get a light-touch confirmation while unmatched addresses receive forms and, ultimately, a door-knock. Applications can also be made year-round, up to the deadline twelve working days before a poll. What no part of the system does is follow a person when they move. Registration attaches to an address, the onus to re-register sits entirely with the elector, and there is not even a way for applicants to check whether they are already registered, which is why hundreds of thousands of pre-election applications each cycle turn out to be duplicates.

The register does more than admit voters

Two versions exist at every council: the full register, used for elections, jury summonsing and credit reference checks, and the open register, an edited version sold to third parties unless the elector opts out. The consequential use, though, is boundary-drawing. The four Boundary Commissions are required to build parliamentary constituencies from registered electors, not resident population, and to keep almost every seat within five per cent of a national quota. The 2023 review worked from the electorate as it stood on 2 March 2020, with a quota of 73,393 electors per seat.

Feed an undercounted register into that arithmetic and the undercount hardens into geography. An inner-city constituency full of unregistered renters looks smaller than it is, gets merged or enlarged, and ends up as one MP for a genuine population that would justify more. Its MP's caseload covers everyone who lives there, registered or not, while the seat count reflects only those on the list. The same skew feeds into council ward reviews and into the local government funding formulas that draw on electorate data.

Why the gap persists

Automatic or assisted registration, using DWP, HMRC, passport or student loan data that already verifies identity, has been recommended by the Electoral Commission and studied by successive governments, and versions of it operate in Canada and much of Europe. Wales has begun piloting automatic registration for its devolved elections under the Elections and Elected Bodies (Wales) Act 2024. For Westminster, ministers have so far preferred the current application-based model, and each electoral cycle therefore opens with the same ritual: a registration drive aimed at the young and the mobile, a late surge, and several million eligible voters still absent from the lists on which both the franchise and the map depend.