[en] Highlights: • Dose accumulation was performed for 322 head and neck cancer patients. • NTCP models were optimized for both planned and delivered dose. • Modest differences between planned and delivered dose were found. • Differences in NTCP models were small for mucositis, dysphagia, and xerostomia. Normal tissue complication probability (NTCP) models are typically derived from the planned dose distribution, which can deviate from the delivered dose due to anatomical day-to-day variations. The aim of this study was to compare NTCP models derived from the planned and the delivered dose for head and neck cancer (HNC) patients.