New rules, which come into force in November, will mean employers wishing to hire staff from outside the European economic area must apply for a licence.
But over half of HRDs surveyed by PricewaterhouseCoopers (PWC) were still concerned about their internal procedures.
In addition, 60% are unsure if they have the systems in place to provide the UK Borders Agency with the information they need to grant a licence.
Julia Onslow-Cole, partner at PWC, said: "UK Borders Agency will only guarantee sponsorship applications received by 1 October will be processed in time, leaving companies facing additional HR challenges at a time of uncertain economic conditions."
Employers not ready for migrant worker laws
Almost nine out of ten employers (88%) have not applied for a sponsoring licence to employ migrant workers.
