People can also cast a special vote if their voting papers are lost or damaged, or they can satisfy the electoral officer that it would be too difficult to cast an ordinary vote, he said.
Voting documents must be returned by noon on October 8 which is polling day.
Preliminary results once all 'ordinary' votes are counted would be available as soon as possible afterwards, with official results expected to be declared between October 13-19.
To register to make a special vote call 0800 ENROL NOW (0800 36 76 56) or obtain enrolment forms at postshops, council libraries or offices up to 4pm on October 7.