family based immigration

• The first preference category consists of unmarried children of United States citizens who are over the age of 21.
• The second preference is divided into “2A” and “2B”. Spouses of lawful permanent residents as well as their unmarried children under the age of 21 fall into the “2A” category, whereas unmarried sons and daughters of lawful permanent residents who are over the age of 21 fall into “2B” category.
• The third preference consists of married children of the United States citizens.
• The fourth preference category consists of siblings of adult United States citizens.

Procedure in general for petitioning  through either the immediate relative category or one of the preference categoriesis to  file an I-130 Petition for Alien Relative with the U.S. Citizenship and Immigration Services (USCIS). This form should be accompanied by the proof of the petitioner's United States immigration status and proof of the relationship between the petitioner and beneficiary. Upon approval of the “I-130 Petition",  the Department of State will determine if an immigrant visa number is available for the beneficiary. Immigrant visas are always available for persons in the immediate relative category. 

However, immigrants in the preference categories may apply for an immigrant visa overseas once a visa number is available. If the beneficiary of the I-130 Petition for Alien Relative is in the United States, they may be able to file an I-485 Application to Register Permanent Resident or Adjust Status with USCIS. If an applicant is outside of the USA and seeking adjudication of his or her Immigrant Visa petition at one of the U.S. Consulates, in most circumstances, the petition will be referred to the U.S. Consulate in the country of the beneficiary's citizenship or permanent residence at the time when the I-130 was approved. Note that in case of a preference as opposed to immediate relative petition, the consulate will not adjudicate the petition until an immigrant visa becomes immediately available for the beneficiary. An immigrant visa becomes immediately available when the priority date indicated on the I-130 Approval Notice becomes current.

Adjustment of status 

If the beneficiary of the approved I-130 immigrant petition is in the United States and seeks Adjustment of Status to that of the Legal Permanent Resident, the beneficiary may only do so when his or her petition's priority becomes current and while the beneficiary is still in a valid nonimmigrant status in the USA. In most cases, the beneficiary's failure to maintain a valid nonimmigrant status while in the United States renders him or her ineligible to seek Adjustment of Status. However, this rule is not applicable to immediate relatives of U.S. Citizens, provided that they have entered the USA using using a valid visa.