Increasing numbers of Australians are choosing to vote early, transforming the traditional election day into an "election period," Australian Electoral Commissioner Tom Rogers says.

Almost a quarter of Australians voted at a pre-poll station in the 2016 election, compared to about 8 per cent in 2007. The AEC does not have a projection for 2019, but Mr Rogers described the growth in early voting as "quite remarkable".

There has been "remarkable" growth in pre-poll voting, according to the AEC. Credit:Cole Bennetts

"When someone pre-polls once we think they become a permanent pre-poll voter," he told journalists at Parliament House on Thursday. "It's become a thing."

Officially, you need a valid reason to pre-poll – such as you will be travelling, working or having a baby on election day. Voters need to declare they meet one of the criteria, but Mr Rogers said there was no way for the AEC to confirm they are telling the truth.