The rise in employer's National Insurance (NI) increases the risk that businesses will resort to making off-the-books cash payments to staff, a study for Stormont's Department of Finance suggests.
From April employers have had to pay NI at 15% on salaries above £5,000, up from 13.8% on salaries above £9,100.
That makes it more expensive for businesses to employ people.
The study by Ulster University academics, which included consultation with business groups, said this risks encouraging the "informal economy".
"There is an increased risk that businesses could return to operating on a cash-in-hand basis only," the analysis from the university's Economic Policy Centre (EPC) said.
It added that it is "important to note this point was only expressed in a small minority of consultations".
The major conclusion from the EPC is that the rise in employer's NI will have a greater impact in Northern Ireland compared to any other UK region.
This is because Northern Ireland is a region where pay is relatively low and the greatest proportional impact of the NI increase is on employers of lower paid staff.
