All individual assessees will have to file their retun by 31st July of the relevant A.Y
Ex: Andal earns Rs. 1,50,000 for the year 2006-07. she will have to file her returns by 31st of July 2007.

For other assessees like "company", "a person whose books of accounts have to be audited under any act", "working partner of a firm whose accounts have to be audited", "a person who is required to file his return under new economic criteria", the due date is 31st October of the relevant assessment year.