BACKGROUND: Informal caregivers' (CGs') subjective burden is an important aspect of the care situation because it is linked to various outcomes such as health, mortality risk, institutionalization, and caregiving style. The aims of this study were a) to examine the convergent and discriminant validity of the 10-item short version of the Burden Scale for Family Caregivers (BSFC-s) and b) to develop a valid classification system for interpreting BSFC-s scores. METHODS: In this cross-sectional study, we analyzed data obtained from 386 informal CGs who applied for an initial grade or upgrade of the care level for the care recipient at the Medical Service of Compulsory Health Insurance Funds of Bavaria (Germany). To validate the BSFC-s, we analyzed the reliability and the convergent/discriminant validity. We calculated correlations with the short form of the Giessen Symptom Complaints List (GBB-24), the Caregiver Strain Index (CSI), the personal further development sub-scale of the Berlin Inventory of Caregivers' Burden with Dementia Patients (BIZA-D), and other scales for establishing informal CGs' situations. To develop the classification system, we compared the percentile ranks of the GBB-24 with the respective BSFC-s sum scores and their distributions and derived three classification categories. RESULTS: Results confirmed the convergent and discriminant validity of the BSFC-s (GBB-24: r = 0.68; CSI: r = 0.70; BIZA-D: r = 0.16; p < 0.001). For informal CGs with low subjective burden, the risk of physical psychosomatic complaints was elevated to a less than average level (BSFC-s scores of 0-4). In those with a moderate subjective burden (BSFC-s scores of 5-14), the risk was elevated. In those with a high burden (BSFC-s scores of 15-30), the risk was substantially elevated. CONCLUSIONS: The BSFC-s is a valid scale for measuring subjective burden in informal CGs. The risk of physical psychosomatic complaints, which is a consequence of subjective CG burden, can be determined by using the valid classification system to deduce the necessity for action and to give concrete recommendations for interventions. The BSFC-s should therefore be employed as a screening instrument in medical contexts and in counseling services for informal CGs.