According to an official notification, the Act comes into effect with its publication in the official gazette.
The Act makes refugees of six minority communities - Hindu, Sikh, Buddhist, Jain, Parsi and Christian from Pakistan, Bangladesh and Afghanistan till December 31, 2014 eligible for Indian citizenship.
The amendment is not applicable to the tribal areas of Assam, Meghalaya, Mizoram or Tripura as included in the Sixth Schedule to the Constitution and in the areas covered under the Inner Line Permit such as Arunachal Pradesh, Nagaland and Mizoram.
Government has said that there is a need to differentiate between intruders and refugees and the Citizenship Amendment Bill does not discriminate against anyone and does not snatch anyone's rights.
The Citizenship (Amendment) Bill was passed by Rajya Sabha on Wednesday and by Lok Sabha on Monday.