Part-time complementary hours
Work out how many extra hours you can be required to do, and which cap binds.
| Pacted cap (30 % of your hours) | 6 h/week |
| Voluntary cap (15 % of your hours)not deducted from the pacted cap | 3 h/week |
| The two percentages added | 9 h/week |
| Headroom to the full-time weekthe total must stay below it | 20 h/week |
| Complementary hours that fit | 9 h/week |
| Contracted hours where the limit changesabove this the legal ceiling binds | 27.59 h/week |
- The complementary-hours pact is specific to the contract and must be made in writing (art. 12.5.a).
- These are not overtime hours: a part-time worker may not do overtime except in force majeure (art. 12.4.c).
- Complementary hours actually worked are paid as ordinary hours and count towards contribution bases (art. 12.5.i).
- Voluntary hours do not count towards the pacted cap, so the two layers add up.
If your collective agreement sets other percentages
Art. 12.5.c) requires the agreement to stay between 30 % and 60 %, and art. 12.5.g) lets it reach 30 % on voluntary hours. If you enter a figure outside those bands, the calculator applies the one the law allows and tells you so.
This tool is educational and does not constitute financial or employment advice.
With no written pact and fewer than 10 hours a week there are no complementary hours. The default reference week is the 40 hours of art. 34.1, and the employer keeps the monthly summaries of the hours record for 4 years. Your agreement's percentages and notice period are facts this page cannot know: enter them if you have them.
The percentage is on your hours, and the agreement can only raise it
Art. 12.5.c) of the Workers’ Statute says pacted complementary hours «may not exceed thirty per cent of the ordinary hours of work that are the object of the contract». The base is your contract, not the company’s full-time week: on a 20-hour contract the cap is 6 hours, and anyone computing it on a 40-hour week frightens themselves with 12. The second sentence of the same paragraph is the one almost nobody quotes: collective agreements «may establish another maximum percentage, which may in no case be lower than the said thirty per cent nor exceed sixty per cent». So the 30 % is not merely the default, it is also a FLOOR on whatever the agreement may set. An agreement fixing 25 % does not lower your cap: that clause is void on the point and your cap is still 30 %.
Voluntary hours are a second layer, and they add to the pacted ones
Letter g) of the same paragraph opens a second route that exists only in indefinite contracts of ten hours a week or more: the employer may offer you complementary hours «of voluntary acceptance» at any time, capped at 15 % of your ordinary hours and extendable to 30 % by collective agreement. The decisive part is its second paragraph: «These complementary hours shall not count towards the percentages of pacted complementary hours established in letter c)». The two layers do not compete, they ADD. By default that is 30 % + 15 % = 45 % of your ordinary hours on top of your contract, and at agreement maxima 60 % + 30 % = 90 %. It also produces an inversion worth knowing: on the same 20 contracted hours an indefinite worker reaches 29 hours a week and a fixed-term one only 26, because the voluntary layer does not exist outside an indefinite contract. The more secure contract is the more exposed one.
The cap that overrides the other two
The third paragraph of letter c) of paragraph 4 says that «in any event, the sum of ordinary and complementary hours, including those previously pacted and the voluntary ones, may not exceed the legal limit of part-time work defined in paragraph 1», and paragraph 1 defines part-time work as a number of hours «lower than the working time of a comparable full-time worker». So the total has to stay BELOW the full-time week, and that means above a certain level of contracted hours the percentage stops being the limit that matters. The crossover is the full-time week divided by one plus the sum of the two percentages: with 40 hours and the statutory caps, 40 / 1.45 = 27.59 hours. A 27-hour contract is limited by the percentage; a 28-hour one is limited by art. 12.4.c), which leaves it less than the percentage would allow.
Which full-time week is compared, because it is not a fixed number
The second paragraph of paragraph 1 does not give a figure, it gives a three-step cascade. First, a full-time worker «of the same company and workplace, with the same type of employment contract, doing identical or similar work». If there is none, the full-time week of the applicable collective agreement. And «failing that, the legal maximum working week», which art. 34.1 fixes at «forty hours a week of actual work on average in annual terms». The 40 hours are therefore the third step of the cascade and not a figure we invented: that is why the calculator carries it as a starting value and lets you change it, because if your workplace has a comparable worker on a different week, the reference is that person’s.
They are not overtime, and refusing is not always punishable
Letter i) of paragraph 5 requires complementary hours actually worked to be «paid as ordinary hours», so they carry none of the premium a reader expects, and letter c) of paragraph 4 forbids a part-time worker from doing overtime at all except in the force-majeure case of art. 35.3. They are two legally distinct things that people merge. On refusing, there are two rules rather than one: letter f) says that where the preceding rules are breached, refusal «shall not constitute punishable conduct», and letter g) says the same of voluntary hours with no condition at all, meaning that declining an offer of voluntary hours is never punishable even when the offer is perfectly lawful. And to leave the pact, letter e) requires fifteen days’ notice, a full year since it was signed, and one of three closed grounds.
Worked example
An indefinite contract of 20 hours a week, in a company whose full-time week is 40. The pacted cap of art. 12.5.c) is 20 × 30 % = 6 hours and the voluntary cap of letter g) is 20 × 15 % = 3 hours, which are not deducted from the first: 9 complementary hours in total, so a 20-hour contract can be asked for 29 hours in a week. The headroom to the full-time week is 20 hours, well above those 9, so here the percentage binds. At agreement maxima (60 % and 30 %) the same 20 hours give 12 + 6 = 18 hours and a ceiling of 38. And the extreme case is a 21-hour contract at those maxima: 12.6 + 6.3 = 18.9 complementary hours against a headroom of 19, so the percentage still binds by a tenth of an hour and the lawful total reaches 39.9 hours a week. A «part-time» contract of 21 hours can end up at 39.9. If it were fixed-term instead of indefinite, the same 20 hours would reach only 26, because the voluntary layer would not exist.
Frequently asked questions
How many complementary hours can I be required to do?
Can my collective agreement lower the 30 % cap?
Do voluntary hours count against the 30 % pacted cap?
Is there an absolute limit above the percentages?
Are they paid as overtime?
How much notice must I be given?
Can I get out of the complementary-hours pact?
What if there is no written pact, or no record of hours?
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Sources
- Estatuto de los Trabajadores, art. 12 (contrato a tiempo parcial y contrato de relevo) · Boletín Oficial del Estado
- Estatuto de los Trabajadores, art. 34 (jornada) · Boletín Oficial del Estado
- Estatuto de los Trabajadores, art. 37.6 (responsabilidades familiares) · Boletín Oficial del Estado
- Real Decreto-ley 32/2021, disposición derogatoria única (deroga el art. 12.3) · Boletín Oficial del Estado
- Real Decreto-ley 11/2024, art. 2 (reescribe los apartados 6 y 7 y añade el 8) · Boletín Oficial del Estado
Author: Thorben Rasmus Idel · Reviewed by: Nahar Geva · Last reviewed: