It’s about to get a lot tougher to get a green card to work in the US.

From October, all those making employment-based applications will have to sit through a one-on-one interview with an immigration official.

Under a shake-up ordered by President Donald Trump, the previously more relaxed approach to those with a job to go to in the States is being substantively beefed up.

Law experts say the process will add possibly months to applications and could lead to more rejections.

Timothy Bakken, an immigration lawyer in the US, said: “Rather than encouraging talented, ambitious, highly-educated immigrants to continue to contribute to our culture and economy, Trump continues to make the immigration process more difficult and less efficient.”

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While those seeking to join family members in the US have ordinarily been expected to undergo interview assessments, that has not generally been the case for economic immigrants.

That all changes from October 1 as the Trump administration continues to target immigration levels with more extreme vetting procedures.

The president has already made a big play to impose the so-called travel ban on a handful of mainly Muslim nations.

US Citizenship and Immigration Services said in-person interviews would provide officers with the opportunity to “verify the information” provided in an individual’s application, unearth new information that may influence the decision, and “determine the credibility” of applicants.

“This change reflects the Administration’s commitment to upholding and strengthening the integrity of our nation’s immigration system,” said acting USCIS director James McCament.

“USCIS and our federal partners are working collaboratively to develop more robust screening and vetting procedures for individuals seeking immigration benefits to reside in the United States.”

Increasingly, the tech industry in the States is attracting workers from across the globe. According to recent UN figures, more than 750,000 Britons are living in the US.

The H1-B non-immigrant visa is for skilled, educated individuals working for a sponsoring employer in specific occupations such as engineering, maths, medicine or law.

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Leon Rodriguez, a former USCIS director under the Obama administration, said the latest measures did not appear to reflect a particular threat of fraud or national security.

“The question is, why? Really, in terms of the ways you could be screening people in for interviews, why is employment-based a risk, compared to other categories and other ways that you might screen for risk?” Rodriguez, now a partner at Chicago-based lawyers Seyfarth Shaw, told CNN.

“And I’m not sure that I’m able to tell you why I would put all employment-based green card applicants at the front of the line for interviews as opposed to anybody else.”

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According to the USCIS, about 180,000 applications could be caught up by the new processing – and the current timeframe of 333 days from application to approval is likely to be extended.

The green card lottery attracts some 15 million applicants each year for only about 50,000 cards. One key aspect of getting a card is that you get to keep it even if you lose your US job.

However, green cards are not forever. They are renewable every ten years, and they can be withdrawn – commonly for committing a serious crime, later discovery that the application was fraudulent or concealed important information, or being out of the US for more than 180 days in a 12-month period.