The Civil Services Application can be submitted Online and Offline by the following dates. It is always suggested not to wait till the last date and to try to submit the application as early as possible.
The last date of submission in March 21, 2011 till 11:59 pm. After which the link will be disabled. The website address is http://www.upsconline.nic.in.
The last date all offline applications must reach by hand, post, speed post or by courier is the 21st March 2011 till 5 pm ONLY. The address to which the applications must be sent is listed below.
"Controller of Examinations, UPSC
Shahjahan Road, New Delhi 110069
For candidates residing abroad or in certain remote localities (as specified by the UPSC) - the last date of receipt for the application is 28th March 2011.