To apply for an immigrant visa to the United States, there are several qualifications that applicants must meet:

1. The applicant must have a qualifying relationship with a U.S. citizen or lawful permanent resident. This could include being the spouse, child, or parent of a U.S. citizen or permanent resident, among other relationships.
2. The applicant must meet certain eligibility requirements regarding health, criminal history, and more. For example, the applicant must not have a contagious disease that would pose a threat to public health, and must not have been convicted of certain crimes.
3. The applicant must submit the appropriate documentation and fees to the U.S. government. This may include a petition or application, as well as evidence of the qualifying relationship and eligibility requirements.

There are several potential limitations or exceptions to these requirements. For example, some individuals may be eligible for waivers or exceptions based on certain factors, such as refugee status or hardship.

If an individual is interested in applying for an immigrant visa to the U.S., it is recommended that they consult with an experienced immigration attorney. The attorney can provide further guidance on the specific qualifications and requirements based on the individual’s unique circumstances, as well as advise on any potential limitations or exceptions.