There are planned some important changes of the taxation of private property sale, which come into force by the 1st of April this year.
From that day the capital gain (the difference between purchase price and sales price) shall be assessed with 25%. If the property is owned for more than 10 years, there is an inflationary compensation of 2% per year. Main places of residence and self- built buildings can be sold without paying tax as always.
For property, which was purchased before the 1st of April in 2002 and which was not converted, there is a taxation of 3,5%; in the case of conversion it's 15%.
Source: http://www.marschall.at/news/detail/news/taxes-of-real-estate-property-change-in-austria.html