Workers at the Scottish Qualifications Authority are to stage three one-day strikes, including on exam results day.
The Unite union had agreed to suspend action amid a restructuring dispute.
But it has now confirmed walkouts on 26 June and 22 July, plus an overtime ban in the week leading up to results day on 6 August.
The union says staff were left in unsuitable roles and a redundancies agreement was breached. The SQA said it was “committed” to addressing issues.
The authority also said it would ensure pupils would receive their results on time.
An SQA spokesman said: “The SQA is fully committed to ensuring that candidates receive their results on time. We have an established governance framework in place, where progress and risks are managed, supported by robust contingency plans.”
‘Lack of confidence’
Unite alleges the restructuring issues “contributed to a lack of trust and confidence in management”.
The union claims that staff were left without specific job roles and that others “had no option” but to accept unsuitable roles.
It stated that if significant progress was not made, then it would trigger the 14-day legal notification for industrial action.
Unite held a ballot and 90% of members who turned out voted to strike.
An overtime ban will also be in place in the week leading up to the day pupils are expected to get their results.
As part of the restructuring process, the SQA launched a voluntary redundancy process which recently ended.
As a result, 62 workers were approved for redundancy, which Unite said was equivalent to 8% of the workforce.
Unite claimed the exercise was concluded “without proper or timely consultation” and breached an existing agreement with the union .
Alison MacLean, Unite regional industrial officer, said: “The situation beggars belief, the workforce are already stressed, demoralised and dismayed. Now to add insult to injury, staff may be expected to pick up additional work.
“Let’s be crystal clear here – this dispute has been created, directed and exacerbated at every turn by SQA mismanagement and incompetence of the highest order.
“Unless immediate action is taken to address our members’ legitimate concerns, then more days of action will be inevitable.”
An SQA spokesman said: “We are committed to working in partnership with the Unite union and have made significant progress on the process that is undertaken in a restructure.
“We are also committed to listen to, and address, the important issues that have been raised by its members. We are focussed on relationship building and moving forward, together, into the future.
“SQA has also concluded its Voluntary Early Release scheme. As an organisation, we continue to evolve our products and services to meet the changing needs of our stakeholders and customers, such as the need to make cost efficiencies.
“The scheme has created opportunities for employees to be considered for voluntary early release from the organisation with financial compensation, where this is of mutual benefit to the employee and to SQA.”