Measures to limit immigration from Bulgaria and Romania when these countries join the European Union in January will include £1,000 on-the-spot fines for staff found working illegally and £5,000 fines for the organisations employing them.
The rules state lower skilled workers coming to the UK from these countries will only be able work in the food processing and agriculture sectors.
But how will these rules be enforced and what effect could they have on employers?
Stephen Carter, spokesman for the Home Office, said although employees will be given on-the-spot fines, for employers, failure to comply will mean prosecution through the courts.
Details of how the law will be enforced are under wraps, but Carter said "intelligence-led operations" will become a Home Office priority and will be carried out wherever there is a "suggestion of illegal practice".
To help employers comply, the Home Office is planning an information campaign backed by a toolkit and helpline, which Carter said is due to be launched before Christmas.
In the meantime, employers need to get up to speed with the new rules. Evan Remedios is a partner of RLegal, a law firm specialising in immigration. He said it is important to understand that the rules do not ban all workers.
"Other highly skilled workers may also be eligible to apply for a work permit. If they can prove they have the skills to do specific jobs, they can apply for a points-tested visa, which will entitle them to work or set up self-employment. Students will also be able to work if they have the correct visa," he says.
However, employers need to be on their guard to ensure staff have the right documentation. "The usual checklist includes looking at their passport, work permit and documents such as their National Insurance number or letter from the Home Office outlining their entitlement to work. Employers will have to tread very carefully, as there is a wide potential to get caught out," says Remedios.
John Davison, chairman of Europeople, a recruitment agency that sources workers for UK firms from Eastern Europe, believes the rules will be difficult for the Home Office to enforce.
"I think the government will f