Hello prabin-rai,

I had same problem in SLC in 2006. At the time, result were not out so the certificate was. So I went to school and they said to visit district education office which in my case was lalitpur district education office since i studied in school located at laltipur district. On visit, they asked me to subject application to correct date of birth written and verified by school. I went to school and got the letter and submitted the application and corrected my date of birth. But I also have found many people were unable to correct this information after they received the certificate and were living with a letter of proof specifying that person with date of birth in slc and person with date of birth in citizenship are same issued by district municipality. However this may be wrong because I recently found this post/article, which also tells what we can we do to correct slc certificate information after certificate has been issued. Please click this link to see this details.