Four seats are up for grabs, and the results will be seen as a temperature check a year out from the state election.
Three of the four are Government-held seats, and should the Coalition lose any one of those, it would be plunged further into a parliamentary minority.
Here’s what you need to know.
With a margin of 21 per cent, Willoughby is considered safe for the Liberals, but there is some disquiet among moderate Liberals, who believe the party’s conservative candidate, Tim James, doesn’t represent their views.
Labor is not contesting the seat, but there are five independents and minor parties in the race, likely to split any protest vote.
Nine News Prediction: The Liberals will suffer a swing, but hold the seat.
Labor is playing to Chinese voters in the electorate with the selection of Jason Yat-Sen Li as its candidate.
He’s been campaigning alongside Mandarin-speaking former Prime Minister Kevin Rudd.
While Ms McKay won in 2019 with an increased margin of five per cent, Strathfield has been a swinging seat in the past, and is being closely watched.
Ms Sakr is a local businesswoman, and is well known in the community. It would be highly unusual for the government to snatch a seat a by-election (where incumbents usually suffer a swing against them), but there is another factor at play.
Due to COVID-19 restrictions, each constituent in these by-elections is being sent a postal vote, which requires a witness signature.
Labor fears non-English speaking voters will be confused by the process and could accidentally lodge invalid votes, largely hindering their base.
Nine News Prediction: Labor will hold the seat with a slightly reduced margin.
Few regions have seen more turmoil in the past two years than those in the south coast seat of Bega, which stretches from Batemans Bay to the Victorian border.
While the outgoing MP, former Transport Minister Andrew Constance, stood tall during the catastrophe, there is now a sense of abandonment among those still battling to move on.
The Liberals are standing local farmer and volunteer firefighter Fiona Kotvojs as his replacement. It is her third tilt at public office in three years.
Labor’s candidate is a well-known local obstetrician, Dr Michael Holland, who has significant name recognition in the northern end of the electorate.
Despite being held by 6.9 per cent, it’s expected to be a tight contest.
Nine News Prediction: A prolonged count will see the seat come down to the wire.
Inland from Bega, the neighbouring electorate of Monaro is also going to the polls to replace former Nationals Leader John Barilaro, whose personal popularity has built the seat into a safe one.
The party has picked Queanbeyan local Nicholle Overall as its candidate, and if she wins, she’ll be the first woman to represent Monaro in the seat’s 165-year history.
She faces a spirited challenge from Labor, with local councillor Bryce Wilson running a strong campaign.
Opposition Leader Chris Minns has likened Mr Wilson to the outgoing Mr Barilaro because of his tenacity.
Nine News Prediction: The Nationals will hold the seat.
By-elections represent a chance for voters to send the government of the day a message, with little overall consequence.
The key on Super Saturday will be for both leaders to listen to what’s being said — and adjust their course ahead of the state election in 12 months’ time.