Yes. This is a page from the government describing your rights: https://www.rijksoverheid.nl/onderwerpen/arbeidsovereenkomst-en-cao/vraag-en-antwoord/wanneer-m

Yes. This is a page from the government describing your rights: https://www.rijksoverheid.nl/onderwerpen/arbeidsovereenkomst-en-cao/vraag-en-antwoord/wanneer-mag-ik-meer-of-minder-uren-werken https://www.rijksoverheid.nl/onderwerpen/arbeidsovereenkomst... (you can translate it) I understand that it is fairly strictly enforced, so an employer saying "no sorry, that would be annoying" won't fly - they would need a concrete justification.