... with more than $300,000 adjusted taxable income.  

The extra tax is 15% of their deductible superannuation contributions.  That becomes a total of 30%.

This can be paid personally or paid through the superannuation fund.  If the superannuation fund pays this amount, this is done by completing the release authority form and provided this is to the Trustees of the fund within 120 days of the date of the letter (which is much later than the due date).

Although this will seem like a penalty, most will still be better off because the marginal tax rate of 47% (in 2013) is still higher the 30% total tax on the contribution.

It is not likely to be repealed by the new government, desperate for tax measures to plug the budget deficit.

Assessments are being issued with the label - Div 293 Deferred Debt.

One additionally annoying feature is the short time to pay – the due date is only shown on the Notice of Assessment – usually much less than 30 days.