I have a bank statement which I download every month as a csv file. The date is given in format 01/12/2015 (or dd/mm/yyy - day/month/year) format. Excel reads this as text. Here is how you convert Text to Date.
Select the Column where the dates are listed. Click on the Data tab. In the Data Tools Group, click on Text to Columns button.
In the Convert Text to Columns Wizard: Select Data Type as Delimited text. Click Next
Selecting the Delimiters: None is necessary since you are working with a single column of data anyway. Click Next
Selecting the Column data format as it currently is displayed in you Excel file. This will be selected in the Date format dropdown box. In my case the format is DMY (Day Month Year). That will tell Excel what is currently the case so that it can recognize the correct format. Also, leave the destination as Cell Address as $B$1. That means the data in the existing column will be corrected and not pasted again to another column. Click Finish
After you have clicked Finish, you will note that the order of the days, months, and year in the dates have changed. Furthermore, notice that where text is aligned left by default, the dates are now aligned to the right.