BackgroundInformal care provided by family members, friends, or neighbors is a major pillar in the German long-term care system. As the number of care-dependent older adults grow, ensuring their future care still relies on the willingness of family members, friends, or neighbors to assume the role of an informal caregiver. This study aimed to investigate the impact on people’s willingness to provide informal care to a close relative with predominately cognitive compared to physical impairments.MethodsAn online survey was distributed to the general population in Germany, which resulted in 260 participants. A discrete choice experiment was created to elicit and quantify people’s preferences. A conditional logit model was used to investigate preferences and marginal willingness-to-accept values were estimated for one hour of informal caregiving.ResultsIncreased care time per day (hours) and expected duration of caregiving were negatively valued by the participants and reduced willingness to care. Descriptions of the two care dependencies had a significant impact on participants’ decisions. Having to provide care to a close relative with cognitive impairments was slightly preferred over caring for a relative with physical impairments.ConclusionsOur study results show the impact of different factors on the willingness to provide informal care to a close relative. How far the preference weights as well as the high willingness-to-accept values for an hour of caregiving can be explained by the sociodemographic structure of our cohort needs to be investigated by further research. Participants slightly preferred caring for a close relative with cognitive impairments, which might be explained by fear or discomfort with providing personal care to a relative with physical impairments or feelings of sympathy and pity towards people with dementia. Future qualitative research designs can help understand these motivations.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13561-023-00448-5.