In 2010/11, a total of 31,217 exceeded the cap, a reduction from 49,786 in 2009/10.
"The cap rules are extremely complex and the reasons for breaches are numerous," MLC head of technical services Gemma Dale said.
"These latest figures suggest investors are seeking the right advice and getting more familiar with the cap rules, however Australians should not get complacent."
The contribution caps were recently halved in July from $50,000 to $25,000 for people aged 50 or over, which could raise the risk of being caught out, Mr Dale said.
A tax penalty of 31.5 per cent is payable for breaches; in some cases it can be significantly higher.
In addition, the ATO has limited discretion to change its assessments.
The number of cap breaches jumped dramatically from 15,831 to 49,786 between 2008/09 and 2009/10 when the cap was halved for the first time.
"It would appear that many people simply weren't aware of the cap changes or didn't do a good job tracking their contributions," Mr Dale said.
"What concerns us now is that the cap has halved again and if history repeats, we could see a big spike in cap breaches in the 2012/13 financial year."
MLC recently launched the latest version of its online contribution cap calculator to help advisers manage the limits for their clients.
