Failing to record a part-time contract's hours means it is presumed to be full-time

The part-time contract carries a recording obligation that many companies still treat as a minor formality: logging the hours worked day by day and totalling them each month. Article 12.4 of the Workers’ Statute attaches a harsh consequence to it. If it is not met, the contract is presumed to have been agreed as full-time, unless there is evidence to the contrary. Two rulings from June 2026 —one from the Madrid High Court and another from the Supreme Court— show the two sides of that presumption: how much it can cost when a company fails to record, and where the limit lies that stops it from becoming automatic.

A part-time cleaner and a regulatory base that doubles

The first case is STSJ Madrid 7758/2026, dated 3 June. A cleaner on an open-ended part-time contract —20 hours a week, half the ordinary working day— started temporary disability leave in January 2023. Her mutual insurer calculated the benefit on a regulatory base of 24.53 euros a day, the figure that came out of her part-time contributions. She was claiming 52.33 euros a day: the amount that would correspond to a full-time job.

Her argument was that the company had never kept a daily record of her hours, so she should be presumed to have worked full-time and the contributions should have been adjusted accordingly.

The Labour Court denied it. It applied the general time-record doctrine of article 34.9 ET: the absence of a record does not by itself mean the working day was full-time, and it was the worker who had to provide evidence of having worked 39 or 40 hours. As she did not prove those excesses, the claim failed at first instance.

The Madrid High Court overturns that reading and upholds the claim. It sets the regulatory base at 52.33 euros a day —1,569.93 euros a month, more than double what had been recognised— and adds something that should worry a company as much as the figure itself: it orders the breach to be reported to the Labour Inspectorate, forwarding the ruling, so that it can act on the under-contribution to Social Security.

Why the part-time contract is governed by a tougher rule

The High Court corrects the lower court on a technical point that is often overlooked: which rule applies.

For an ordinary contract, the burden of proof over hours worked follows the doctrine of article 34.9: if the schedule is fixed in advance and met as normal, the lack of a record does not automatically shift the proof of compliance onto the company; it is the worker who must provide evidence that there were excesses. That is the rule the lower court applied, and for a full-time contract it would have been correct.

But the part-time contract has its own regime in article 12 ET, and that regime is more demanding on the employer. Section 4.c) requires the part-timer’s hours to be recorded day by day, totalled each month, and the summary handed to the worker together with the payslip, keeping it for four years. And it closes with an explicit consequence: failing to meet those recording obligations presumes the contract to be full-time, and the one who has to prove otherwise —to show that the work was genuinely part-time— is the company, not the worker. Where article 34.9 splits the burden in the employer’s favour when there is a fixed schedule, article 12.4 flips it against the employer the moment the part-time record fails.

The underlying reason is not formalistic. The part-time record exists to prevent the most common abuse in these contracts: agreeing few hours on paper and demanding many more in practice, with no trace left behind. The law reinforces oversight at the point where the worker is most exposed. In the cleaner’s case, the company provided nothing to prove that the working day was genuinely part-time, so the presumption applied in full: a full-time schedule of 39 hours a week under the Madrid building-cleaning collective agreement, a recalculated contribution, and a higher benefit.

The limit the Supreme Court places on the presumption

Twelve days later, the Supreme Court issued STS 2742/2026, dated 16 June, which acts as a counterweight. A ground-handling worker at an airport, on an open-ended part-time contract, claimed that his relationship should be declared full-time because the contract did not detail the distribution of his hours, as article 12.4.a) requires. The Labour Court ruled in his favour; the Canary Islands High Court overturned it.

The reason he lost defines the scope of the presumption. The one in article 12.4 is iuris tantum: it allows evidence to the contrary. The employer’s formal breach triggers the presumption of full-time work, but it does not simply turn a part-time contract into a full-time one if it is established that the work was genuinely part-time. And in this case that evidence to the contrary was supplied by the worker himself: in his statement of claim he acknowledged that he did not work full-time. With that admission, his claim was left without a basis.

The Supreme Court dismisses the appeal on a contradiction defect —the two rulings being compared did not hold opposing doctrines, but decided differently on different facts— and confirms the line it had already set in several 2026 decisions: the presumption works as a shift in the burden of proof, not as an automatic conversion of the contract. The nuance matters in litigation: the presumption can be rebutted, but to rebut it you need something to rebut it with. A daily record of the part-timer’s hours, kept properly and preserved, is that evidence; without it, the company reaches trial with nothing to set against the full-time work presumed of it.

What this means for a company with part-time contracts

The two rulings, together, map out the risk precisely. The full-time presumption is not a theoretical threat: in the Madrid case it translated into a regulatory base that doubles, a recalculation of contributions, and a report to the Inspectorate. And it is not triggered by working extra hours, but simply by not recording. Merely failing to keep a daily record of the part-timer’s hours is enough for the burden of proving that the working day was genuinely part-time to fall on the company.

The practical problem is that this evidence is hard to reconstruct after the fact. When the claim arrives —from a worker, from Social Security, or from the Labour Inspectorate— there is rarely a reliable trace of the hours actually worked month by month. The signed contract remains, but not the record backing it up, and the presumption does the rest.

The draft Royal Decree on time recording tightens this ground even further: it requires daily and monthly totalling, traceability of changes, and four-year retention. These are, almost point for point, the same obligations that article 12.4 already imposes on the part-time contract. The difference is that under the new rule they will stop being a scattered sector-specific requirement and become the general standard.

How a digital record neutralises it

With digital clock-in like Cleverfy, the part-time worker’s hours are recorded day by day with their exact time, totalled automatically each month, and that summary can be handed over with the payslip, which is what article 12.4.c) requires. If a dispute later arises over whether the working day was part-time or full-time, the company has the evidence to the contrary that the presumption demands, instead of having to reconstruct it when it is already too late. The same record that protects the employee against fictitious part-time work is what lets the company prove part-time work when it is real.

See how Cleverfy works and check how simple it is to keep the record that stops a part-time contract from being presumed full-time.

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STS 2742/2026 is final. STSJ Madrid 7758/2026 may be appealed in cassation for the unification of doctrine before the Supreme Court. Sources: STSJ Madrid 7758/2026 (CENDOJ, ECLI:ES:TSJM:2026:7758) and STS 2742/2026 (CENDOJ, ECLI:ES:TS:2026:2742).