Rotorua also had the second highest number of trespass notices issued over the same period.
PSA union staff representative Kathy Higgins said the socio-economic mix in Rotorua may mean more people were using Winz services, which in turn could lead to a higher number of incidents.
Higgins said the Ministry of Social Development had started taking incidents more seriously following the 2014 Winz shootings in Ashburton, "as they should".
The ministry's deputy chief executive corporate solutions, Stephen Crombie, said the safety of staff and clients was an "absolute priority – no one should come into a Work and Income office and feel threatened or scared".
"Our zero tolerance for people who demonstrate threatening and abusive behaviour towards our staff and clients means that some incidents that may not have been recorded in the past now are.
"Additionally, some threats and incidents that previously may have been considered to represent a minor risk are now interpreted in context of the potential worst case outcome, resulting in a rise in reported security incidents, and more definitive actions being taken."
Staff had, on average, more than 1000 face to face meetings with people in Rotorua every week, he said.
"Since the Ashburton tragedy in September 2014, and following an independent review of our sites' security, we started a new programme focused on improving our security processes. As a result we've made a number of enhancements to our Work and Income service centres throughout the country, including in Rotorua."
Winz had strengthened its zero-tolerance approach to threats and abuse, was doing more training for staff, such as de-escalation techniques, and practised regular safety drills, he said.
"We have regular team discussions about safety and promoting a more risk-aware culture and have also implemented a new health, safety and security operating model. As mentioned above, we've improved the reporting and analysis of incidents, and have increased the number of security guards at our client-facing sites to support our staff during security incidents.
"We're also reviewing our health, safety and security policies and procedures and also designing changes to the physical layout of our client-facing sites and have duress alarms.
"We've also successfully trialled an enhanced security design incorporating a zoning model at two sites and have introduced this to another three recently relocated sites and are looking at opportunities to do this at other sites."
WINZ sites with the highest number of incidents between 2015-2017
Whanganui Service Centre- 289
Palmerston North Main Street Service Centre- 281
Rotorua Community Link- 264
Waitakere Community Link- 241
Whangarei Central Community Link- 171
