England - South Cambridgeshire District Council sent out 7,500 ballot papers for tenants to vote for representatives on a housing association committee.
Among those were 533 papers for people who had died.
"We apologise in particular to the relatives of those people for any distress this caused," a spokesman for the council said.
"Due to an administrative error some voting papers... have been sent out to a number of people who are no longer tenants of the council either because they have moved away, given up their tenancy, or regrettably, have passed away," the spokesman said.
Officials said the voting papers would be reissued and a new election held.