3 September 2012 at 14:44
The change could be due to a number of reasons:
1. The travel allowance amount has changed;
2. Business km's traveled decreased;
3. A different car was used which could result in the cost per km being less;
4. You are also limited to the number of actual km's you may claim for business travel.
If you would like to send me the tax calculation that SARS has done or the ITA34 to firstname.lastname@example.org I can have a look.