When you make extra contributions to your super through salary sacrifice, you’re adding to your super before income tax is deducted. Because super is generally taxed at 15%, depending on how much you earn, making before-tax contributions to your super can provide a tax-effective way to boost your super savings.
Salary sacrifice contributions are included in the concessional (before-tax) contributions cap, along with the super contributions your employer makes for you and after-tax contributions you claim a tax deduction for. This cap is currently $27,500 pa. From 1 July 2019, you can carry forward any unused portion of the concessional contributions cap for up to five previous financial years, depending on your super balance. You should consider your debt levels before adding to your super.