The government has ditched the idea of setting up a website to allow people to check if they are registered to vote.
Millions applied to vote in the run-up to the general election and EU referendum but most wasted their time because they were already registered.
The only way to check is to contact your local council.
Officials were swamped by duplicate applications and there were fears about a rise in "double voting" with people registered in two places.
The Electoral Commission said urgent action was needed to deal with the problem and called for an online "look up" service to be set up, preferably as part of the existing online registration service, which has proved highly popular since it was launched in 2014.
But the government has rejected the idea on cost grounds after carrying out a study.
Cabinet Office minister Chris Skidmore said he would not be publishing the results of the "online registration status checking survey".
But he said: "The results of the assessment were that such a service is both impracticable given significant technical and security considerations and very expensive.
"Indeed, as set out previously, the cost of such a service would far exceed the cost of processing duplicate applications."
He added that the "need for citizens to be able to check their registration status has not been clearly identified".
"There is, however, a clear need for citizens to be confident they can apply to register to vote quickly and easily.
"This is met by the existing online service, which has now seen more than 30m applications. Citizens with questions about their registration status can contact their local elections office directly," he said in a written Parliamentary statement.
Labour's shadow voter engagement and youth affairs minister Cat Smith said: "Extreme Tory cuts since 2010 have left local authority elections teams without the necessary resources to increase the number of people registered to vote.
"The creation of an online service to enable people to check if they are registered to vote should be properly explored and it's disgraceful the government is refusing to look into the idea.
"Labour is in favour of increasing voter registration in our democracy but once again the government is standing in the way."
There was a surge in applications to vote in the run-up to last year's EU referendum and June's general election.
Between 1 December 2016 and the 22 May deadline, about 4.9 million applications to vote were submitted, the majority of them done online.
But the net increase in the number of entries on the electoral register during that period was only 1.4 million, suggesting most were likely to have been duplicates.
The proportion of duplicate applications is estimated to have ranged between 30% and 70% in different areas.
There is no national electoral register in the UK. Information on who is registered to vote is held on 380 separate databases by local authorities and by the chief electoral officer in Northern Ireland.
There is no direct link between these local databases and the online registration service, meaning it is impossible to check if an applicant is already registered.
"The relative ease of submitting an application to register to vote using the online service, in comparison to the difficulty of contacting a local authority electoral services team by telephone or email to check if they were already registered, meant that many people simply submitted another application," said the Electoral Commission in a report on the general election.