Divorce is different from annulment, which declares the marriage null and void. Reasons for divorce vary, from sexual incompatibility or lack of independence for one or both spouses to a personality clash or infidelity.

Nullity of marriage can be sought under section 11 of the Hindu Marriage Act 1955 and section 24 of the Special Marriage Act. The procedure and timeline for the disposal of a nullity is the same as for a divorce petition.

A marriage can only be solemnised between any two Hindus if the following conditions are fulfilled:

• Neither party has a spouse living at the time of the marriage.
• Neither party is mentally impaired or insane at the time of the marriage.
• The bridegroom is 18 years or over and the bride 15 years or over at the time of the marriage.
• The parties are not within the degrees of prohibited relationship, unless the custom or usage governing each of them permits of a marriage between the two.
• The parties are not sapindas (that is, lineal ascendants of each other or have a common lineal ascendant as far as third generation (inclusive) in the line of ascent through the mother, and the fifth (inclusive) in the line of ascent through the father, unless the custom or use governing each of them permits a marriage between the two).
• Where the bride is under the age of 18 years, the consent of her guardian in marriage, if any, has been obtained for the marriage.

Only the violation of the prohibition of bigamy and marriage within a prohibited relationship renders the marriage void. Being underage does not render the marriage void or voidable. Insanity renders a marriage voidable.

Under the Special Marriage Act 1954 and the Hindu Marriage Act 1955, there is a distinction between a void and voidable marriage. The Indian Divorce Act 1869 only provides grounds on which marriages are void, but provides no grounds on which a marriage is voidable. This is the same under the Parsi Marriage and Divorce Act 1936, although some of the traditional grounds on which a marriage is voidable have been made grounds of divorce.

Muslim law recognises only void marriages known as batil marriages (that is, a marriage that does not exist from the outset). There is no concept of voidable marriage. No court decree is necessary. Even when the court passes a decree, it merely declares the marriage null and void. Muslim law has a unique concept of irregular marriage called fasid marriage.

A voidable marriage is a valid marriage if it is not avoided. A voidable marriage can be avoided only on the petition of one of the parties to the marriage.