For A client we have build an API connection to ZOHO.
Therefore we use: ZohoReportPHPClient

Importing, updating etc works fine. 
But we have only one strange issue with the some date fields.
We are offering the date like this: 31-03-2011
But then it's converted to this: 03-07-2013

This only happens when we use the API, when importing the same csv file manually we don't have the issue. 

Is there any specific date format that is expected when importing with the api?

While writing this issue I see that the API offers the possibility to define a date format with: ZOHO_DATE_FORMAT

But still usefull for me to know if en what default date format zoho uses for importing over the API and if it's correct that this will differ from manual import.