Employment-based immigrant visas are a type of visa that allows foreign nationals to come to the United States for work purposes. There are five different employment-based visa categories, each with its own eligibility criteria:

EB-1: Priority Workers
This category is for people with extraordinary ability in education, sciences, arts, business, or athletics. They can be outstanding professors and researchers and certain multinational executives and managers.

EB-2: Professionals with Exceptional Ability
This category is for individuals with advanced degrees or exceptional abilities in the sciences, arts, or business.

EB-3: Skilled Workers, Professionals, and Other Workers
This category is for individuals with at least two years of experience in a skilled occupation, a bachelor's degree or equivalent, or unskilled workers in certain industries.

EB-4: Special Immigrants
This category is for individuals such as religious workers, employees of U.S. foreign service posts, retired employees of international organizations, and certain other groups.

EB-5: Immigrant Investors
EB-5 visa is for individuals who invest a minimum of 1 million USD (or 500,000 USD in certain areas) in a new commercial enterprise in the United States that creates at least 10 jobs for U.S. workers.

In order to be eligible, 

• You must have been offered a job by a U.S. employer.
• The employer must have obtained a labor certification from the U.S. Department of Labor.
• You must have the education, experience, and/or skills required for the job offer.
• You must meet the criteria for the subtype you are applying for.

While applying for this visa, you must provide the following documents,

• A valid passport for travel to the United States with a validity date of six months beyond your period of stay in the U.S.
• Your employer must obtain a certified labour certification from the U.S.
• Department of Labor to show that there are no qualified U.S. workers available for the job offered to you.
• You must provide documents to show that you meet the education, experience, and/or skill requirements for the job offered to you. 
• You must provide a police clearance certificate or similar document from each country you have lived in for six months or longer after the age of 16.
• You must go through a medical examination by a designated physician to ensure that you meet the health requirements.

The process of application is the same for all five employment-based visa types Both the employer and the employee are supposed to play their part. The application process must begin with the employer, with the exception of the investment visa (EB-5) scenario.

Visa Processing Time
Processing timeframes are lengthy because there are yearly restrictions on the number of employment visas that can be issued. They can last anywhere between a few months and three or more years until the priority dates become current. The number of applicants who came before you will determine everything.

How to Apply
Follow these steps while applying for this visa,

• Get a labour certificate and file for the visa.
• Submit the documents required for this visa.
• Attend the visa interview if needed and wait for the confirmation.

Duration
Once the immigrant visa is issued, the duration of the visa will depend on the specific category. For example, an EB-1 visa is generally valid for up to 10 years, while an EB-2 or EB-3 visa may be valid for up to 6 years.

Fees
Generally, the fee includes two parts: a filing fee for the immigrant petition (Form I-140) and a fee for the visa application itself. As of 2023, the filing fee for Form I-140 ranges from 700 USD to 1,440 USD, depending on the specific visa category. The visa application fee for Employment-Based Immigrant Visas is currently 345 USD, which is payable at the time of the visa interview.

Can we extend an employment-based immigrant visa in the US?
Yes, it is possible to extend your employment-based immigrant visa in the US. You must apply for the extension before your previous visa expires.

Can I bring family members with me on an Employment-Based Immigrant Visa?
Yes, you are allowed to bring your spouse and children under the age of 21 with you on your Employment-Based Immigrant Visa.