Australians have until 8pm on Thursday to make sure they are on the electoral roll and eligible to vote in next month's federal election.
People who have moved house in the past three years also need to update their details on the electoral roll by 8pm.
Electoral commissioner Tom Rogers said people could enrol or update their details at the Australian Electoral Commission website.
He reminded people that all citizens aged 18 and older were legally required to enrol and vote.
"We've had hundreds of thousands of enrolment transactions submitted since the election was announced and there are now only hours left for people to sort out their enrolment," he said.
"If they're not on the roll, they'll need to complete an enrolment form as soon as possible today and get it to the AEC before the deadline of 8pm."
People who are unable to enrol online can collect a paper enrolment form from any electoral commission office or most Australia Post outlets.
They must be returned to a commission office or uploaded to aec.gov.au/return by the 8pm deadline.