You can make a full tax deduction for super payments you make for employees, provided the contribution is made to a super fund to provide superannuation benefits for an employee.
Salary sacrifice contributions are also a deduction for your business, provided you have a written agreement in place with each employee making salary sacrifice contributions to super.
All tax deductions apply for the financial year in which you made the contribution.
You cannot claim a tax deduction for voluntary post-tax contributions made by your employees as tax has already been applied to the employee’s income.
If you are self-employed, you can make a full deduction for voluntary contributions you make to your own super.