Cricket Australia will allow Big Bash clubs to sign nationally-contracted players outside of their salary cap in a bid to avoid the Steven Smith fiascos of the past two seasons.

Under rules unveiled by CA on Wednesday, players will be able to sign with individual clubs on a marquee supplementary list if they are not expected to be available to play.

Should the player's circumstances change, they will then be able to be brought into the BBL's club's full-time roster to feature in matches. The rules come as part of a raft of contracting changes for the men's and women's BBL, including the introduction of an overseas player draft in the WBBL in the same model as the men's tournament.

The highest-paid overseas men's player will command $420,000 in the draft, while the female counterparts will collect $110,000 in a major boost to the pulling power of the competitions.

Clubs will also have to pay their top-six men's earners a minimum of $200,0000 each, and top-five female players $50,000 each. But the biggest change will come with nationally-contracted men's stars.

Franchises will be able to contract as many as they like inside the $3 million salary cap for their regular 18-man roster, as well as two additional players outside of the cap. Those players would be on a standardised $50,000 deal.

If they end up playing, only then will their $50,000 deal and $30,000 match fees count to the cap. If the player's availability comes through unforeseen circumstances, CA will also allow clubs to bring money out of the following season's cap to fit them in.

That would likely only be activated for any player who has been dropped from Australian duties, or if international fixtures were to change. The new rule would cover both of the Smith scenarios in the past two years, where Covid-19 caused the cancellation of a series in early 2022 and home ODIs earlier this year.

Smith was unable to play for the Sixers in 2021-22 as he was not signed with them, while he and David Warner were handed marketing contracts last summer to play for the Sixers and Sydney Thunder, respectively.

The new system would also allow the likes of Mitchell Starc, Josh Hazlewood and Pat Cummins to be aligned with clubs and appear in marketing material, with the quicks traditionally sitting out the BBL to manage workloads.

CA hopes the changes open the door to more big-name talent playing, while allowing clubs to not have roster spots and significant cap space taken up by unavailable players with Tests in January this summer.

"It's always our ambition for as many of those players to be part of the BBL as possible," Big Bash boss Alistair Dobson said. "We hope that the mechanisms will enable clubs to sign players even if they are either unlikely or not available. Because having them around the BBL and ready if available, is a really important part of the competition for us."