Answer
TFN Declarations do need to be completed by your employees, however, they do not need to be physically sent into the ATO any longer, since Single Touch Payroll reports all of the relevant tax coding to the ATO with each submission.
Make sure to configure the employee's tax settings in the program as per their TFN declaration, under Employees >> Tax Rates and this information will be reported along with Single Touch Payroll. Keep the paper declaration (or the employee tax details summary from ATO online) securely in your own records, in case the ATO asks for it. If the employee gives you a new declaration, or you stop paying them, keep the old one until the end of the following financial year. For example, if you last paid them on 12 April 2026, keep it until 30 June 2027.