https://www.sbs.com.au/news/why-does-australia-have-compulsory-voting

What happens if you don't vote?

According to the Australian Electoral Commission, people who fail to vote will be sent a letter asking to provide a legitimate reason or pay a $20 fine.

If they fail to pay the fine or provide a valid reason for not voting, the matter will be sent to court.

The AEC states: "If the matter is dealt with in court and you are found guilty, you may be fined up to $180 plus court costs and a criminal conviction may be recorded against you".

Professor McAllister said there was no reliable data on how many people are fined each year for failing to vote however he said it was estimated to be about 2000-3000 people per year.