Depends when the shares vested. If they vested in the 2023...

Depends when the shares vested. If they vested in the 2023 financial year (which is a broad period don't forget - 01 July 2022 to 30 June 2023), tax return would need to be submitted by 31 October 2023 or 15 May 2024, then the ATO assesses and issues your debt to pay with a timeframe, usually by 21 November or 5th June, however you can negotiate for an extension or payment plan.

Also plenty of people lodge their returns late, including through a tax agent, so the timeframe payments are due can really differ. Best to speak to an accountant if you aren't sure.