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How to Apply Salary Supplements: Part I

Salary supplements or additions to base salary are amounts added to the base salary under any of the headings established in a collective bargaining agreement or in an individual employment contract.

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Such supplements constitute financial entitlements granted to the employee in return for work performed, which are added to the base salary to make up the total overall remuneration.

TYPES OF SALARY SUPPLEMENT:

    PERSONAL SUPPLEMENTS:

    · Length-of-service allowance:
The length-of-service supplement is an amount paid to the employee solely by virtue of having remained employed by the same company for a specified period of time.

The traditional purpose of this supplement is to encourage the employee to remain with the company, with the aim of offsetting the costs the employer may have incurred in staff training, whilst also rewarding the loyalty and commitment shown by the employee.

These factors have largely lost their relevance today, but similar instruments are emerging, such as retention agreements and stock options, which we have discussed in other articles in this publication.

The supplement is typically calculated by paying a set amount for each completed period of service. This amount may take the form of a fixed sum or a percentage of the salary.

As regards the calculation of the salary supplement, although a large number of collective agreements provide that length of service begins to accrue from the date of joining the company, where no specific provision is made it is generally understood that accrual begins from the date the employee commences employment.

It should be noted, however, that only the period during which the contract is in force is to be taken into account.

    HAZARD, HARDSHIP AND TOXICITY SUPPLEMENTS:

These are salary supplements that compensate the employee for working under particularly demanding or hazardous conditions.

Their recognition depends, in all cases, on the free agreement of the parties, who may or may not choose to acknowledge their existence. In practice, collective bargaining arrangements use various approaches to designate activities as eligible for these supplements:
    - By agreement between the company and employee representatives.
    - By decision of the company's management.

    · Hazard allowance:
This supplement applies where the role carries an additional risk arising from the inherent danger of performing the job in circumstances where an attack or injury is a real possibility. Examples include firefighters and staff working in psychiatric hospitals.

    · Hardship allowance:
This supplement applies where work is carried out under exceptionally demanding conditions, involving activities that require sustained physical or mental effort and are undeniably arduous. Examples include working in environments with high levels of noise or dirt.

    · Toxicity allowance:
The toxicity supplement applies where the role involves the use or handling of substances that pose an exceptional health risk to the employee.

    SUPPLEMENTS FOR WORKING HOURS ARRANGEMENTS:

These supplements recognise the special time-related circumstances under which work must be performed.

Their primary purpose is to provide financial compensation for the greater availability, time commitment, or burden involved in working particular schedules, shift patterns, days, or under certain conditions.

    · Availability allowance:
This supplement compensates employees who are required to remain subject to the company's organisational authority beyond their normal working hours, making it impossible or significantly difficult for them to engage in other paid activities outside of those hours.

This salary allowance may only be established as a result of:
    - A unilateral or agreed decision by the company, or
    - A demonstrable pattern of persistent changes to the employee's working schedule.

The availability allowance accrues by virtue of the mere fact of being on call, that is, being at the company's disposal and ready to be called upon to perform work at any time.

    · Flexible hours allowance:
This allowance is designed to allow the employer to freely determine employees' start and finish times.

It also serves to compensate for the adaptation of working time to the exceptional requirements of certain services, or as a form of remuneration for work performed on Sundays and public holidays.

    · Public holiday supplement:
This is structured as a allowance which, in addition to being offset by a rest day on another day of the week, also attracts additional pay.

Its purpose is to compensate for the inconvenience of working on Sundays or public holidays, where this is required by the nature of the role.

This allowance applies to employees working standard hours; it does not apply to those hired on a part-time contract specifically to work on Saturdays and Sundays.

    · Extended hours supplement:
This supplement is characterised by its ability to allow the employer to call upon those employees whose presence may be essential at a given moment, and who, on that basis, are required to work outside their regular working hours.

In this case, the supplement compensates for work that is more extensive and prolonged than usual, with the particular feature that entitlement to receive it lapses once the reason for it has ceased to exist.

The courts' interpretation regarding entitlement to this supplement is that the extension of working hours is applied at the company's discretion; the company may decide at any time whether work is to be carried out during standard or extended hours, while the employee retains the freedom to accept or decline.

    · Special dedication supplement:
This supplement requires the employee to remain available to their direct line manager whenever called upon, beyond their standard duties. The purpose of this allowance is to provide additional remuneration in recognition of the employee's voluntary acceptance of full availability in their role.

Its distinction from overtime lies precisely in this element of full availability. Unlike overtime, this supplement does not relate to extraordinary activity but rather to a specific characteristic of the particular role, given that working overtime is voluntary for the employee.

    · Night work supplement:
The purpose of this allowance is to provide additional remuneration to compensate for the greater discomfort associated with carrying out professional duties during night-time hours.

Night work is defined as work performed between ten o'clock at night and six o'clock in the morning. A night worker is an employee who regularly works at least three hours of their daily working day during night-time hours.

What this allowance compensates is not the shift itself, but rather the hours actually worked during the period legally defined as night-time.

If the salary was set with specific regard to the night-time nature of the work, the supplement is not payable, in that case, night work forms an essential part of the contract, and the remuneration was agreed precisely on that basis.

Date published: 31 August 2003

Last updated: 2 September 2026

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