Substantial Modification of Working Conditions in the Company: How to Implement an Individual Measure and Avoid It Being Declared Unfair or Void
A material change to terms and conditions of employment is one of the most powerful, and sensitive, tools in employment law. When properly used, it allows an employer to adapt its organisation to new operational or technological realities without resorting to more drastic measures. However, if improperly implemented, it may be challenged before the employment tribunals, potentially resulting in an adverse decision requiring the measure to be reversed or, in more serious cases, the payment of compensation.
This article addresses the individual substantial modification of working conditions, governed by section 41 of the Workers’ Statute. The collective regime, which triggers a consultation procedure with employee representatives (the works council/employee representatives) and is subject to its own formal and negotiation requirements, will be analysed separately in a subsequent article.
What Working Conditions May Be Modified by the Employer under Section 41 of the Workers’ Statute
Not every change to working conditions constitutes a substantial modification.
Section 41 of the Workers’ Statute reserves this mechanism for changes affecting specific matters, namely working time, working hours, shift patterns, work and performance systems, job duties, or remuneration systems. These are precisely the conditions that have the greatest impact on an individual’s day-to-day working life. For this reason, the legislator requires the employer to demonstrate the existence of economic, technical, organisational or production-related grounds justifying the decision.
However, it is not sufficient for the employer to be justified in principle; it must also be able to prove it.
The individual procedure requires written notification to the affected employee, with a minimum notice period of fifteen days. Such notification must set out the measure adopted, its effective date, and the grounds justifying it. The employee then has three options: to accept the change, to terminate the employment relationship with entitlement to compensation of twenty days’ pay per year of service (capped at nine months’ salary—the lowest statutory compensation under the Workers’ Statute), or to challenge the measure before the labour courts.
Obligation to Inform Employee Representatives (Works Council)
This is a point that is often overlooked by companies. Although this is an individual modification—and not a collective one—section 41(3) of the Workers’ Statute requires the employer to simultaneously notify its decision to the employee representatives, where they exist. This is not a consultation or negotiation procedure, but rather an obligation to provide information. Failure to comply with this requirement does not automatically invalidate the measure; however, it may be relied upon in a challenge to question the employer’s good faith in managing the process or to allege a breach of the right to freedom of association.
Case Study: Change of Work Shift in a Manufacturing Company
To understand how a properly substantiated material change to terms and conditions of employment should be structured, there is no better approach than a practical example.
A shower tray manufacturer operates two production lines on morning and afternoon shifts. In the packaging department, there are two lines: an automated line operating on the same morning and afternoon shifts, and a manual packaging line operating only on the morning shift. Over time, an operational issue is identified affecting day-to-day workflow: production exceeds packaging capacity. A classic bottleneck.
The company decides to take action. It invests in replacing the manual packaging line with a new automated line. In order not to abruptly alter the working conditions of the team assigned to that line, it maintains their morning shift pattern.
However, it is identified that the new automated packaging line—despite its greater technical capacity—packages approximately 40 fewer shower trays per day than the other, older automated line, which operates on a shift basis. The difference therefore does not lie in the technology, but in the organisation of work.
The company concludes that the solution no longer lies in new technology, but in harmonising the shift system: the packaging line should operate under the same regime as the rest of the department, namely morning and afternoon shifts. The measure is proportionate, is based on an objective production-related ground, and there is a clear logical link between the issue identified and the measure adopted: three requirements that the courts typically require and which are clearly met in this case.
How to Justify Selection Criteria in an Individual Material Change to Terms and Working Conditions
Where an individual material change to terms and conditions of employment affects only some employees within a group—and not all those performing equivalent duties—the employer must be able to justify why certain employees are selected and others are not. This is one of the most sensitive issues in practice.
Section 41 of the Workers’ Statute does not set out a statutory list of selection criteria, as is the case, for example, in collective redundancies. However, this does not mean that the employer may act arbitrarily. The courts have been clear: where the measure applies selectively to certain individuals, the employer must demonstrate that the selection is based on objective, non-discriminatory criteria linked to the underlying grounds justifying the change.
In the example of the shower tray manufacturing plant, the selection is straightforward: the measure affects those working on the affected production line, which is precisely the one giving rise to the production imbalance. There is no selection between employees performing equivalent roles, but rather a material change to terms and conditions of employment linked to the job position and production line. This is the ideal scenario.
Where the situation is more complex—for example, where several employees perform similar roles and only some are subject to the change—it is advisable to document the criteria applied, such as length of service, shift availability, family circumstances that may give rise to protected adjustments, or any previously formalised individual agreements. Undocumented selection is the quickest route to a legal challenge.
Traceability, Proportionality and What Remains Unchanged
The modifications that withstand judicial scrutiny best share one common feature: they can be explained in a coherent sequence. They have a clear beginning, development and logical outcome. In the case under analysis, the sequence is clear: a bottleneck; technical investment; provisional maintenance of working conditions; identification of insufficient performance; and a proportionate measure.
Such traceability does not arise automatically. It requires productivity reports, performance comparisons, and internal data supporting the diagnosis, as well as a coherent explanation as to why the measure adopted is appropriate and not a less onerous alternative. If this documentation does not exist prior to notifying the change, it is difficult to build it afterwards with the same level of credibility.
How to Draft a Notification of Modification of Terms and Working Conditions to Withstand Legal Challenge
This is the point at which companies most often fail. The decision may be correct, the underlying grounds may be genuine, and the supporting data may exist; however, if the communication is reduced to a mere verbal instruction or a generic letter referring to “organisational needs” without further detail, the legal defence of the measure is significantly weakened.
Notification to the affected employee is not a mere procedural formality. It is an opportunity to clearly explain what has occurred, the data supporting it, the alternatives considered, and why the measure adopted is necessary, appropriate and proportionate. A well-drafted communication may even prevent a legal challenge. By contrast, a poorly drafted communication can turn a legitimate decision into unnecessary litigation.
Where possible, it is advisable to seek an agreed solution. There is nothing preventing the employer from implementing a material change to terms and conditions of employment on a consensual basis, formalising individual agreements with those employees who accept the change, and reserving the unilateral material change mechanism for those who do not. This sequence—first dialogue, then decision—conveys an image of orderly management that is generally well regarded by the courts.
Key Considerations for Implementing Section 41 of the Workers’ Statute with Legal Safeguards
The individual material change to terms and conditions of employment under section 41 of the Workers’ Statute is not a shortcut. It is a tool which, when properly used, enables employers to adapt to new realities without unnecessarily undermining employees’ working conditions. However, it requires rigour: substantiated grounds, justified selection criteria, notification to employee representatives, full and transparent communication, and robust prior documentation.
For employers, the recommendation is clear: anticipate. Before communicating the change, prepare the supporting file. Before notifying the affected employee, analyse the underlying grounds, identify the data supporting them, assess the available alternatives, and design a communication capable of withstanding judicial scrutiny.
To properly manage this type of process, it is essential to obtain specialist employment law advice from the diagnostic stage through to the final communication of the measure. At DEVESA, we support companies in the planning and implementation of strategic employment decisions, helping them to mitigate risks and strengthen the legal certainty of their internal processes.
In the next article, we will analyse the substantial modification of collective working conditions: numerical thresholds, the consultation procedure with employee representatives, the content of the negotiation, and the consequences of defective processing.
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