Relatively few $100 polymer Australian banknotes have been returned to the RBA for processing, the central bank admits in its Bulletin for September 2019.
The life expectancies are:
• a little over 5 years for the $5 and $10;
• a little over 10 years for the $20; and
• around 15 years for the $50.
This, Aves notes “is consistent with lower-denomination banknotes incurring higher wear through greater use for transactions”.