The Cabinet Office minister says it's not possible to say how many voter registration letters have been returned to sender.
David Ashford faced a question in the House of Keys from Arbory, Castletown and Malew MHK Jason Moorhouse, asking for figures on voting forms.
Mr Ashford said a total of 45,842 forms were sent out to households, with 12,000 registrations already completed online.
He explained returned forms aren't counted, as this would be a time-consuming exercise with around five months to go until the general election in September:
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