Objective The Carer Support Needs Assessment Tool (CSNAT) was developed in the UK and has been shown to be effective to assess and address support needs of family carers of terminally ill patients at home. In German language, there is a lack of an evidence-based comprehensive assessment tool for family carers in palliative home care. The objectives of this study were to translate and develop a culturally adapted version of the CSNAT for a German-speaking context including the assessment of feasibility, face, and content validity. Method A translation and validation study was conducted in three steps: (1) translation of CSNAT following International Society for Pharmacoeconomics and Outcomes Research criteria; (2) cognitive testing in five German-speaking regions in Germany, Austria, and Switzerland with 15 family carers; and (3) pilot testing in palliative home care services. Evaluation was by telephone interviews with those involved in the assessments (family carers, health care professionals) and a focus group discussion with the health care professionals. Data were analyzed using content analysis. Results The regional idiomatic variety raised challenges in the process of translation. Cognitive testing revealed semantic, conceptual, syntactic, and idiomatic issues. During the pilot, 25 assessment conversations were held. Carers reported that the German version called KOMMA was brief, easy to understand and to complete, and helpful. They appreciated that the items adequately addressed their support needs and reminded them of their own strengths and resources. Health care professionals observed good acceptance by carers, the expression of unexpected patterns of needs, and extensive assessment conversations, but some raised concerns that the assessment process might shift attention to carers' needs at the cost of the patients. Significance of results A multi-step process of translation, cognitive testing, and pilot testing led to a culturally well-acceptable German tool (KOMMA). Comprehensibility, acceptance, face, and content validity, as well as feasibility were demonstrated.