This starts for small employers on 1 July 2019. For large employers this started the year before.
In practice all employers will need to be using a computer payroll system connected to the Internet. When you prepare the pay for an employee the information including the 9.5% super will be lodged with the ATO computer automatically.
The theory is that the ATO will immediately know what is owed to them for PAYG and what has to be paid to the super fund. If you have trouble meeting these tax and super deadlines it will be very easy for the ATO computer to come and hunt you down. You thus need to ensure that you have the funds available at each payroll date, not just for the net wages, but also for the tax and super.
Please talk to us if you have cash flow issues. There are many and varied solutions for this.