The Excess Concessional Contributions are counted as personal assessable income taxed at the marginal tax rate. Learn more from the ATO
LodgeiT has a worksheet to help with concessional and non-concessional contributions tax.
Fill via "Estimate" page
Scroll through Division 293, make sure to toggle "Yes" the "Show Division 293 tax?"
Then, press the "Edit" > "Additional tax on concessional contributions (Division 293)"