The lay caregiving role is integral to advanced cancer care but places carers' health at risk. A supportive General Practitioner (GP) can help primary lay carers manage their health, if they disclose their concerns. A Needs Assessment Tool for Caregivers (NAT-C) was developed for carers to self-complete and use as the basis of a GP consultation, then tested in a randomised controlled trial. This paper reports a qualitative research study to determine the usefulness and acceptability of the NAT-C in the Australian primary care setting. Convenience samples of 11 carers and 5 GPs were interviewed between September 2010 and December 2011 regarding their experiences with and perceptions of the NAT-C. Open-ended questions were used, and the transcripts were analysed qualitatively to identify themes and patterns. Three major themes were identified: (a) Acceptability of the intervention (b) Impact of the intervention on the GP-patient relationship and (c) Place of the intervention in advanced cancer care. This simple checklist was acceptable to carers, although some were uncertain about the legitimacy of discussing their own needs with their GP. Carer-patients could not be certain whether a GP would be willing or equipped to conduct a NAT-C-based consultation. Such consultations were acceptable to most GPs, although some already used a holistic approach while others preferred brief symptom-based consultations. Although the NAT-C was acceptable to most carers and GPs, supportive consultations take time. This raises organisational issues to be addressed so carers can seek and benefit from their GP's support.