This means they need to ensure that their freelancers are indeed deemed to be self-employed by HM Revenue & Customs (HMRC).
The taxman concentrates on areas where he expects tax may be underpaid, and so-called 'status' (where someone is either an employee or self-employed) is a lucrative area for him.
Companies would have to provide a list of dates when freelancers worked, copies of contracts and invoices, and a description of what they did.
If HMRC decides a freelancer has been used by a firm for too long, or on too regular a basis, it could deem that freelancer to be an 'employee'.
With this judgement, the company will be forced to pay any underpaid employer's tax (PAYE) - retrospective for up to five years - and National Insurance contributions.
What's more, HMRC could charge interest and a fine, too.
Don't get caught out - if freelancers look and behave like employees, HMRC will likely deem them as such.
Richard Fifield, managing director, Tenon Outsourcing.