Can you work overtime on a part-time contract?

“Can you work overtime on a part-time contract?” comes up the moment an employee on reduced hours stays a little longer. The law forbids it: overtime has no place in part-time work. There is a separate figure for extending working time, complementary hours, governed by different rules. Confusing the two is one of the most common causes of penalties in part-time work.

Quick answer

Item	On a part-time contract
Overtime	Forbidden (art. 12.4.c ET)
Exception	Only force majeure
Complementary hours	Yes, if agreed in writing
Agreed complementary hours	Up to 30% of working time (60% by agreement)
Time record	Mandatory, with monthly totals and a copy to the worker

Why overtime doesn’t fit

Article 12.4.c) of the Workers’ Statute puts it plainly:

“Part-time workers may not work overtime, except in the cases referred to in article 35.3.”

That article 35.3 covers force majeure: the hours needed to prevent or repair emergencies and other extraordinary, urgent damage. Outside that, a part-time worker cannot work overtime even if they wanted to and the company asked. The ban exists to stop part-time work being used as a disguised, worse-paid full-time job.

Complementary hours, the legal alternative

The fact that overtime doesn’t fit doesn’t make a part-time contract rigid. Extending working time has its own channel, complementary hours, and they work differently:

• They are paid as ordinary hours, without the surcharge or the treatment of overtime.
• They count for social-security contributions.
• They must be agreed in writing, in the contract or in a later specific agreement.
• They have their own cap, separate from the 80-hour limit on regular overtime.

In practice, when a manager wants a half-time employee to work a few extra hours, those hours are not logged as overtime; they are agreed in advance as complementary hours.

How many complementary hours can be agreed

There are two types, and they should not be mixed:

Agreed complementary hours. They require a written agreement and cannot exceed 30% of the contract’s ordinary hours. The collective agreement can raise that share to 60%, but never lower it below 30%. The company can require them with minimum notice.

Voluntary complementary hours. These are only possible if the contract has working time of at least 10 hours a week on an annual basis and they are offered as such. They have their own cap (up to 30% of ordinary hours, extendable by collective agreement) and, being voluntary, the worker is not obliged to accept them.

One detail that often slips: complementary hours add to the agreed working time, but the total can never effectively turn the contract into a full-time one on a sustained basis. If the extra hours become the norm month after month, the risk goes beyond the fine: the real working time can be presumed to have been full-time.

The risk of getting it wrong

Logging as overtime what in a part-time contract can only be complementary, or making someone work more with no agreement at all, has two consequences:

• A labour offence, punishable by the Labour Inspectorate.
• Conversion of the contract. If in a lawsuit the worker shows they regularly worked more hours than agreed, without complementary-hours cover, courts can presume the real working time was higher, with the pay and contribution difference that drags along. It is the same ground we cover in part-time contracts without a record and the presumption of full-time work.

The evidence decides everything. Without a reliable record, the company cannot prove how many hours were actually worked, and in part-time matters the burden of proof falls on it.

Time tracking for part-time work is stricter

Part-time work carries a reinforced recording duty compared with the rest of the workforce. On top of the daily clock-in and clock-out record, the company must:

• Total monthly the hours worked, both ordinary and complementary.
• Hand the worker a copy, with the payslip, of the summary of all the month’s hours.
• Keep the records for four years.

Doing that in a spreadsheet is where control is lost, and where the Inspectorate finds the discrepancies. A time-tracking software like Cleverfy records the real time with an unalterable timestamp, separates ordinary from complementary hours, warns when someone is nearing their agreed cap, and generates the monthly summary ready to hand to the worker or the Inspectorate. With the new Royal Decree on time tracking on the way, that record will also have to be digital and tamper-proof.

Conclusion

On a part-time contract there is no room for overtime except for force majeure; the only way to extend working time is complementary hours, with a written agreement, their own cap and payment as ordinary hours. Working beyond the agreed hours without that channel exposes the company to a penalty from the Inspectorate and, if the hours become regular, to the working time being presumed full-time with the pay and contribution difference going four years back.

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Legal note: informational article, not legal advice. Based on articles 12 and 35 of the Spanish Workers’ Statute. Collective agreements may set specific conditions; check yours before making decisions.

Sources:

• Workers’ Statute, Art. 12
• Workers’ Statute, Art. 35