Sesame HRWorkforce Management
Complementary hours and their legal regulations. The agreement of complementary hours allows companies to optimize workforce management by enabling part-time employees to work additional hours beyond their contracted schedule.
Isabel García
HR Consultant
3 of February, 2025
Everyone knows what overtime hours are: those performed outside of regular working hours. However, the same cannot be said about supplementary hours.
This is a key concept when we have part-time workers. The regulations establish that they must result from an agreement between the employer and employee.
Supplementary hours are those additional hours agreed in writing that are performed outside the ordinary workday in part-time contracts.
Remember that part-time work prevents overtime hours. Therefore, if it is necessary to extend the workday, we must resort to additional hours.
Supplementary hours are often used to deal with work peaks with existing staff. Thank to these additional hours, there is no need to resort to additional hiring when the workload increases.
We could say that they are the equivalent to overtime in part-time contracts, and the key is the written agreement.
Firstly, you should know that the supplementary hours agreement appears as an annex to the employment contract.
Once they have been agreed, supplementary hours are added to the total of the employee’s regular workday. The employee cannot refuse to perform them and end the workday upon completing his regular schedule.
It is also important to point out that these extra hours can be applied to part-time contracts, both temporary and indefinite.
There is just one requirement: exceeding 10 hours weekly. If the regular work schedule is less than these 10 weekly hours, supplementary hours cannot be established.
The number of agreed supplementary hours cannot be exceeded. In that case they would be considered overtime, which as we saw is incompatible with part-time work.
If it is necessary to increase them, it would be necessary to renegotiate the supplementary hours agreement and extend them.
Another key aspect is the three-day notice. This agreement cannot be signed from one day to the next, but requires at least 72 hours notice.
In fact, in the agreement itself we can extend this period depending on what was agreed upon. The Collective Agreement also gives us a reference.
The Ministry of Labor provides a model of a supplementary hours agreement. You just have to download the document and complete the various fields according to what was agreed upon.
The document consists of eight clauses, including the duration, notice or the voluntariness of them.
This is a critical question for two aspects. To begin with, in the supplementary hours agreement, it must reflect how many hours will be made.
And the second aspect, no less important, is limited to 30% of the ordinary hours of the work contract. For example, if you work 20 hours per week, you can perform up to 6 extra hours.
As usual, we can find exceptions in the sector’s collective agreement, or in the company’s. This can increase the extraordinary hours up to 60% of the ordinary working day or reduce the total.
In any case, the sum of supplementary and ordinary hours cannot exceed the legal limit of part-time work.
Although it is not specified in the supplementary hours agreement, these are paid as ordinary hours. At the end of the month, they will be included both in the payroll and in documents related to Social Security.
These are hours that count for grace periods, bases of benefits or Social Security itself.
Keep in mind that supplementary hours are always paid.
The employer cannot change them for additional breaks when the work peak that has necessitated their performance finishes. This is one of the main differences between supplementary hours and overtime.
For this very reason, it is fundamental to have control and register of supplementary hours.
To do this, having a human resources software like Sesame HR is fundamental. On the one hand, we ensure the hourly control of workers according to regulations.
On the other hand, we complete the tracking of workers’ supplementary hours. We make sure not to exceed the legal limits established at any time, such as the 30% cap.
In addition, it will be easier for us to transfer them directly to the workers’ payroll.
Another important aspect is the duration of supplementary hours.
How long can this workday extension be prolonged? Once signed, it can be extended indefinitely. As we have seen, we can update it if it is necessary to extend the working day.
Only after 12 months can the employee renounce the supplementary hours agreement. To do this, he must accredit one of these three assumptions:
Beyond the agreed supplementary hours, voluntary supplementary hours can also be made.
Their operation is somewhat different from the agreed ones. For example, only those workers with indefinite part-time contracts can perform them.
In this case, a written agreement is not necessary and they are limited to 15% of the ordinary workday.
As in the case of the agreed ones, the collective agreement can double this percentage to 30%. The limitation to part-time contracts over 10 hours is maintained, and being voluntary the worker can refuse to do them without risk of sanction.
Did you find this interesting? Discover more about time management and supplementary hours on the Sesame HR blog.
I'm Isabel, HR consultant at Sesame HR. Book a meeting with my team to help you.
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