Let Reporting Services use the User’s regional settings

US format by default

When designing a report currencies and dates use the US format, e.g. MM/dd/yyyy The user would like to read his report in his local format, e.g. dd/MM/yyyy.

Change the report for the user’s regional settings

In the report designer change the report property Language to Expression: =User!Language

A more elaborate explanation can be found at this link Reporting services tip about user regional settings