Dear Rajesh, to be honest, thats a big error thay has happened. Unfortunately, CLAT doesn't even have a correction window. However, you can try reaching out to their helpdesk. The last date for submitting the applications is March 31st. So assuming today you send a mail to the helpdesk and even if they take a month to reply (which is not the case) you will still have time to fill in a new application. We understand that the fees is a hefty amount but its better to go to the exam hall with a relief knowing that all the details in your application are correct. To be honest, at the exam hall lets say you explain the invigilator the issue and he/she is generous enough to let you appear for the exam (they wont). You still have to attend the counselling. There no one would accept this. Its a throat cut competition and too many students compete for one seat. So they cannot overrule your mistake and give you a seat. In this process, you might be even held for malpractise. Its rather better you reach out to the helpdesk and wait for their reply. If they give you a chance to correct your Date of Biryh, you are clear. But if they dont, you will have to fill in a new application form and make another payment.