Do you employ staff? If the answer is “yes”, then you will need to contact your software provider and start preparing for the 1 July 2019 mandatory start date with respect to reporting ‘year to date’ figures for gross, tax and Superannuation liabilities on each pay event. The ATO have indicated in press releases and bulletins to Tax Agents that they will not be issuing extensions to businesses who have failed to plan for the STP system. See link at Single Touch Payroll
TIP: The 20 employees include all full-time, part-time and even certain casuals.