The Rail Maritime and Transport union (RMT) will seek backing for walkouts on Sundays and a ban on working on days off.
It follows an agreement between ScotRail and drivers’ union Aslef for drivers to be paid extra for working on days off being extended from last month to October.
The practice was due to have been ended by the recruitment of more drivers, making “rest day” working unnecessary, but this has been put back by Covid restrictions delaying their training.
The RMT was angered by the move after being told its members would not be getting a pay rise at a time when drivers were benefiting from the second year of a previously-agreed two-year increase.
The row follows a dispute three years ago which caused long-running disruption after drivers won a deal which saw them paid more than conductors and other staff for working on rest days.
Scottish organiser Mick Hogg said: “My members are spitting blood and are frustrated that they are being treated with absolute contempt.
“They have been kicked in the teeth and when we are down, we have been kicked in the teeth again.
"Absolutely disgraceful this decision.”
RMT general secretary Mick Cash told members: “The union's national executive committee has recently considered the matter and I have been instructed to write to Abellio Scotrail advising we are in dispute with the company over their refusal to negotiate a rest day dynamic payment for all grades.
"The ballot for industrial action will be for strike action in which members will be instructed not to work Sundays and for action short of a strike in which members will be instructed not to work any rest days or undertake higher grade duties.
"The executive committee has instructed for the ballot to commence as soon as possible for the conductor grade and then they will give further consideration to balloting other grades separately, excluding drivers, at a later date.”
Jim Baxter, Aslef’s executive committee member for Scotland, said: “In the wake of the problems caused by the pandemic, Aslef has agreed to move the end date of the current rest day working agreement from January 30 to October 30.
“Aslef has a long-standing agreement with ScotRail that allows drivers to work their days off, if they choose.”
ScotRail operations director David Simpson said: “Thanks to emergency support from the Scottish Government, we haven’t furloughed any of our staff, there have been no job cuts, and indeed no cuts to core salaries or terms and conditions.
"So it is very disappointing the RMT has chosen to create unnecessary disputes which risk causing a distraction, rather than focus on securing jobs and helping the business recover from the worst crisis in its history.
“We will wait for further detail from the RMT and respond accordingly, and we hope that there will be an attempt to engage with us meaningfully, ahead of any action that would potential cause disruption for those who need to use our services.”