So many potential voters are currently missing from the electoral roll that the next UK-wide poll could be based on a “flawed franchise”, the Electoral Reform Society (ERS) has warned.
The organisation is now calling on the Scottish Government to explore how it can use its powers to ensure more people are signed up to vote in time.
It follows a recent survey by the Electoral Commission that found between 630,000 and 890,000 people in Scotland who are eligible to be on local government registers are not correctly listed, with between 400,000 and 745,000 entries classed as inaccurate - typically caused when a voter changes their home address but fails to notify the authorities.
As the completeness of the parliamentary and local registers are nearly identical, campaigners believe that hundreds of thousands of people are missing from the electoral roll.
Young adults and those living in urban areas are more likely to be incorrectly registered, with those living in cities with high student populations particularly at risk of missing out on voting.
Boris Johnson has repeatedly called for a snap election to be called in recent weeks, but opposition parties have refused to back the required Commons vote to dissolve parliament until a potential no-deal Brexit has been ruled out.
Despite the impasse, all the major parties are now on an election footing and preparing for what could be the first Westminster poll held in winter months for 45 years.
Dr Jess Garland, director of research at ERS said: “These figures should sound the alarm for anyone who cares about democracy. Hundreds of thousands of potential voters in Scotland are effectively missing from the electoral roll, representing a major barrier to political equality and democratic engagement. That means any snap election will be on the basis of an flawed franchise.
“You shouldn’t have to opt in to your right to vote. As the Electoral Commission says, we need to move towards automatic registration now, starting with being able to check you are registered online, and being able to register whenever you engage with government bodies or services. There’s widespread consensus on this - now it just needs to be done.”
Alice Kinghorn-Gray, a campaigns officer for ERS in Scotland, said: “We urge the Scottish Government to explore how it can use its powers to ensure everyone has a stake in our democracy.
“The gaps in registration are creating major inequalities in our elections, with young people and renters particularly affected. Parties must respond with action, and start to bring in the ‘missing millions’. Let’s ensure the next election does not exclude huge swathes of our country and instead represents the gold standard for participation.”
A Scottish Government spokeswoman told The Scotsman: “It is important that everyone who is entitled to vote ensures they are registered to do so in time for any forthcoming election.
“The annual canvass of voters is currently underway – and every residential property in Scotland is being sent a letter requesting details of any resident who may be entitled to register. Anyone identified as not being on the electoral register will then be sent an invitation to register.
“Electoral registration officers produce interim registers in the run-up to any poll, but voters can register up to 12 working days before the day of any election.”