The concessional contributions cap generally includes any contribution for which a tax deduction has been claimed.
For 2020/21 the standard concessional contributions limit is $25,000 regardless of age. This limit is subject to indexation but may not increase each year.
If you exceed the concessional contribution cap, the excess is added back to your assessable income for the financial year and taxed at your marginal tax rates. However, you will be entitled to a 15% tax credit on the excess amount added to your income representing the contributions tax already withheld by the super fund. Tax penalties may also apply. If the excess is not refunded it will also count against the non-concessional contribution cap.
Please note: Since 1 July 2018, a new carry forward provision applies for concessional contribution caps. This means that any unused portions of your concessional contribution caps can now be carried forward for up to five years as long as your total superannuation balance does not exceed $500,000. Once you exceed this threshold, the carry forward provision will no longer be available for you to use, however the $25,000 concessional contribution cap will still apply. The first year you will be entitled to carry forward unused amounts is the 2019-20 financial year. This will be beneficial for those who take career breaks or have lumpy income.