Yes, your understanding is correct. Salary sacrificed contributions count towards the co-contribution income test, and this has been the case for quite a few years; specifically since the start of July 2009 (that is, from the start of the 2009/2010 financial year and for future financial years, including the 2013/2014 year and beyond).
What this change means is that individuals on higher incomes, seeking to access the co-contribution scheme, cannot use salary sacrificing (that is, make before-tax super contributions to their super fund), to lower their income to a level that allows them to receive the tax-free Government co-contribution.
The co-contribution is a tax-free super contribution from the Federal Government when you make a non-concessional (after-tax) contribution. If your ‘total income’ is $33,516 or less (for the 2013/2014 year), the Federal Government pays $0.50 for every dollar you contribute to your super fund in after-tax dollars, up to a maximum of $50 a year. If your ‘total income’ is more than $33,516, your co-contribution entitlement reduces by 3.33¢ for every dollar you earn over $33,516, until it cuts out at $48,516.
Background: Previously, that is for the 2008/2009 year and earlier financial years, the co-contribution ‘total income’ threshold was: assessable income, plus the value of any fringe benefits that you have as part of your salary package, such as a car. Since the 2009/2010 year onwards, the ‘total income’ definition also includes salary sacrificed contributions. Note that assessable income also includes bank interest and net capital gains from selling shares or property.
For those readers who want to know more about the Federal Government’s co-contribution scheme, I provide a summary of the scheme in my article Cashing in on the co-contribution rules (2013/2014).