Working part-time doesn't simply mean earning "less" than full-time: it involves a specific proportional calculation that affects your salary, your contributions, and other employment rights, and it's worth understanding well to check that your payslip is correct.
The principle of proportionality
The general rule governing part-time contracts is proportionality relative to a comparable full-time worker: your salary, your vacation days, your seniority, and virtually all your financial rights are calculated by applying the percentage your working hours represent of the full-time hours set as reference in your collective agreement or company.
How the proportional salary is calculated
Part-time salary = Full-time reference salary × (your hours ÷ full-time hours)
For example, if the salary for your job category at full-time (40 hours a week) is €24,000 gross a year, and you work 20 hours a week (50% of full-time), your proportional salary would be €12,000 gross a year.
How social security contributions are calculated
Contributions are also calculated proportionally to the hours worked, which means the future benefits you build up (unemployment, pension) will also be calculated on contribution bases proportionally lower than those of a full-time worker earning the same hourly rate.
The part-time coefficient and its effect on your future benefits
For calculating certain benefits (especially the retirement pension), a part-time coefficient is applied to periods worked part-time, which has led to lawsuits and regulatory changes in recent years to prevent workers with long part-time careers (frequently women) from being clearly disadvantaged compared to equivalent full-time workers when it comes to accessing certain benefits.
Additional hours: a concept specific to part-time contracts
If your contract expressly allows it, the company can ask you to work additional hours beyond your agreed schedule (horas complementarias), subject to maximum limits and a minimum notice period, with specific agreed pay for them, distinct from the concept of overtime that exists in full-time contracts.
How to check whether your part-time payslip is correct
The most direct way to check is to calculate the exact percentage your hours represent of the full-time hours in your collective agreement, and apply that same percentage to the full-time salary for your job category, comparing the result with what your actual payslip shows.
Calculate your proportional net salary
Our net salary calculator lets you enter your gross annual salary (already calculated proportionally) to estimate your actual monthly net salary.