Do you know where you'll be on Saturday, October 25? If you live in the State electorates of Newcastle or Charlestown, it's something you should be considering.

By-elections for both seats were made necessary when the sitting Liberal MPs, Tim Owen and Andrew Cornwell, resigned over revelations at the Independent Commission Against Corruption.

But unlike a normal election, if you planned being away from home you would not be able to drop into a polling place elsewhere and lodge an absentee vote.

There were a couple of options available on election day - October 25 - voting early and voting by post.

Richard Carroll from the NSW Electoral Commission said they were expecting a lot of pre-poll votes.

"If people don't feel that they can get to a polling place on election day for whatever reason, for work, or looking after a family member or travelling, they should take advantage of early voting options," he said.

"That's certainly been the trend over the years, the number of people who are voting early goes up election after election.

"So we're expecting to get a lot of people voting before election day."

Mr Carroll recommended early voting for people whose plans might change at the last moment, so they did not get "caught short".

"Because, of course, voting is compulsory," he said.

Pre-poll voting was now available at the returning office for each electorate.

The Newcastle office was at 158 Darby St, Cooks Hill, and Charlestown's was at Shop 5, 158 Pacific Highway, Charlestown.

It was possible to vote for either electorate at both locations, which were open from 8am until 6pm weekdays, 9am until 5pm on Saturday, and from 8am until 8pm on Thursday, October 23.

Returning offices would be closed on Sundays, but voters could have their say up until 6pm on the Friday night before the by-election.

The other option was postal voting, and you could either download an application form from the Electoral Commission website or call 1300 135 736.

Mr Carroll said the number of people using postal votes declined every year but it was still convenient for some, including elderly people with limited mobility.

You could find a list of your local polling places, as well as information about the nine Charlestown candidates and eight Newcastle candidates, at the Elections NSW website.

Richard Carroll spoke to Paul Bevan from 1233 ABC Newcastle Drive.