Unison has urged its Scottish members to return a "Yes" vote
More than 100,000 council staff in Scotland have been balloted for strike action amid a pay dispute.
The 2.5% deal would mean rises of as little as 15p per hour in the first year, according to public sector union Unison.
The other unions representing council staff, GMB and Unite, also rejected the offer and will ballot their members in July.
Councils have warned they have to operate within limited resources.
The Unison ballot will include members working for Scotland's 32 local councils, local joint valuation boards and fire and rescue staff.
Unison regional organiser Dougie Black said council umbrella organisation Cosla had failed to address concerns over the rejection of their "inadequate" offer and it was now clear that members had to deliver a "Yes" vote.
He added: "They have failed to tackle the issue that the offer increases the gap between the higher and lower paid.
"At the bottom end the offer means a mere 15p per hour increase in the first year."
Local government unions want an increase of 5%, or £1,000, but councils have offered an increase of 2.5% a year for the next three years.
Unison members in England, Wales and Northern Ireland earlier voted to take strike action over a 2.45% offer.