Abstract Introduction Timely identification of needs due to functional loss in old age is important. Policy guidelines requires local collaborative care action. Eldercare debut circumstances are poorly investigated from a collaborative perspective. This study explored the socio-demographic characteristics, functional status and patterns of health care use leading up to the first application for eldercare, and how older people’s intensity of primary care use was associated with their intensity of granted eldercare at debut. Methods Data on socio-demographics, functional status, and informal care in people ≥65 years (July ‘21 to June ‘22; n = 3,649) were combined with data on inpatient and outpatient care six months preceding debut in Stockholm, Sweden. Descriptive and regression statistics were used. Results Every second person debuted following a hospital stay and one in four had extensive functional limitations. The majority made one or two visits in primary care, but 13% had a high intensity of use and 20% made no visits at all. More than half received informal care weekly or daily. Non-use and high use of primary care were both significantly associated with increased probability of receiving high intensity of eldercare. Conclusions and implications The intensity of primary care use can provide an indication of people’s intensity of eldercare at debut, which is important for resource allocation. Deeper collaboration between eldercare and primary care actors can facilitate early identification of people in need of support, thereby alleviating individual suffering, enabling secondary and tertiary prevention, and optimizing the management of welfare resources. Key messages • The intensity of primary care use can provide an indication of people’s intensity of eldercare at debut. • Deeper collaboration between eldercare and primary care actors can facilitate early identification of older people with social support needs.