Members of the Fire Brigade Union Scotland (FBUS) rejected the offer, which would have seen their basic pay rise in stages to July 2022 by 14.74% compound, with an overall increase of 17% compound.
But the union said the deal was conditional on firefighters and control staff taking on "significant new areas of work," including co-responding to slips, trips, and falls and a broadened role in supporting vulnerable people. Its members voted against the deal by a margin of 60% to 40%, with turnout at 81%.
Denise Christie, the FBU Scotland secretary, said: “Our members have turned out in their masses at meetings across Scotland and to vote in this ballot. The consensus is clear; we want and deserve a pay increase, but the offer in its current form is unacceptable."
Matt Wrack, the FBU general secretary, added: "In negotiations, we were concerned that this offer would not be acceptable to our members in Scotland – and this clear result serves as proof. Firefighters are emergency responders but are no substitute for social care staff. This offer was a step too far in that direction."
Mr Wrack said that the union was "entirely open" to discussions about securing a service "fit for the the challenges of the future," and that it was "not the time to walk away from negotiations.
An original pay offer from the Scottish Fire and Rescue Service was rejected by union members last July.
Martin Blunden, chief officer of the Scottish Fire and Rescue Service, said: "We have spoken with the Fire Brigades Union, and while it is regrettable that we have been unable to reach an agreement, we respect the outcome of the ballot.
“We have been in a unique position in Scotland, having secured funding from our government, to bring forward a 17 per cent pay offer to broaden the role of Scottish firefighters."
He added: “As this offer has been rejected there will be no further Scotland-only pay offer as there is now no additional funding and we will re-join the UK wide National Joint Council negotiations on firefighter pay.
“However we remain absolutely committed to protecting Scotland’s communities from harm and identifying ways to meet new and emerging risks.”