If you are 75 years or older, the super fund cannot accept any voluntary (concessional and non-concessional) contributions from you apart from mandated (super guarantee) employer contributions which can be contributed at any time regardless of age.
However, the SIS Legislation also allows for a 28 day period from the end of the month in which a member turns 75 years to make member voluntary contributions (concessional or non-concessional) and salary sacrifice contributions to the fund subject to satisfying the work test condition.
Where the contribution is received but does not meet the above rules, the trustees are required to refund the contribution within 30 days of becoming aware.
Example: Adam is a member of ABC Superannuation Fund
On 6 October 2015, Adam turns 75 years old.
Provided Adam meets the work test condition, the trustee can accept and record the amount as a contribution as it has been made within 28 days from the end of the month in which he turns 75 years.