Amid a Trump administration crackdown on the controversial H-1B visa, the federal government has issued a list ranking the reasons why it delays applications with requests for more evidence for why an employer and worker should get a visa.

Earlier this week, U.S. Citizenship and Immigration Services released data showing that over the past three years it had increased its rate of denial and delay for H-1B visas. While Silicon Valley tech giants like Apple, Google and Facebook received nearly every visa they asked for, outsourcing companies’ applications were approved at lower rates. The rate of H-1B approval dropped to 85 percent in 2018 from 96 percent in 2015, the data show.

Now, Citizenship and Immigration has put out a ranking of the top reasons it demanded “requests for evidence” in 2018 from employers seeking the lottery-based visa, which is intended for jobs requiring specialized skills. The No. 1 reason, according to the agency? “The petitioner did not establish that the position qualifies as a specialty occupation.”

Bay Area technology firms rely heavily on the H-1B, lobbying to increase the annual 85,000 cap on new visas. But the visa has come under attack in the wake of reports of abuse by outsourcing companies, and critics charge that businesses use the H-1B to supplant American workers with cheaper foreign labor. The administration of President Donald Trump has promised to reform the visa program to root out abuse, and has imposed new rules for applicants.

On Citizenship and Immigration’s list of reasons for delaying H-1B applications, the second-most-common was failure by a company applying for a visa to prove it had a valid employer-employee relationship with the visa candidate, in which the applicant company has the right to control the visa holder’s work.

Next on the list was failure by the applicant company to establish it has qualifying off-site work for a visa candidate in a specialty occupation for the entire duration of the visa requested. The fourth-most-common reason was failure by the employer to prove that the H-1B candidate was qualified to perform services in a specialty occupation.

Here is the entire list of 10 reasons for evidence requests.