The advent of the 'gig economy' means that the distinctions between workers, employees and independent contractors can be harder to determine; the recent high profile Uber decision demonstrates this. Accordingly, any businesses purporting to use a self-employed model should be aware of the potential risks of being investigated by the immigration authorities. 

The same point applies to agency workers who may seek to assert that they are employees of the end user, rather than the agency. Businesses need to ensure that any agencies they use are carrying out the correct right to work checks and also that there is wording to this effect in the relevant contract with the agency, including appropriate warranties and indemnities.

If the immigration authorities are of the view that the staff are employees and, if any of those staff are working in the UK unlawfully, then a failure to carry out right to work checks can result in a civil liability penalty of up to £20,000 per illegal employee. Further, the Immigration Act 2016 reduced the threshold for the existing criminal offence from 'knowing' that a person is an illegal worker to 'having reasonable cause to believe' someone is an illegal worker. Conviction on indictment for this offence could lead to a prison sentence of up to five years and no contractual warranties or indemnities will be able to pass the criminal liability to another party. 
In particular, employers in the vulnerable sectors (the three 'C's - care, catering and construction) may want to consider checking everyone who comes on site, including volunteers and independent contractors, so they can make an informed decision about whether to proceed.

If someone is completing tasks on an employer's behalf, no matter in what capacity, there is the potential for reputational damage if the member of staff is working beyond their visa conditions or without an appropriate visa at all. It is much better to sort out any right to work issues early, rather than once the immigration authorities are involved, because defending a civil penalty can be costly.