This paper considers how a diagnosis of dementia affects people's planning for future social care needs and associated costs. It addresses the gap in knowledge about how people recently diagnosed with dementia, and their family carers, engage with planning for social care needs that are uncertain in timing and scale. The paper also considers people's attitudes to planning for care that they may need to pay for privately, and what facilitates or hinders acting on such plans. We conducted and undertook thematic qualitative analysis of 39 in-depth interviews with 27 people newly diagnosed with dementia and/or their carers over a two-year period. Topics included current care and support, planning and co-ordinating care, paying for care, and expectations and planning for the future. The research took place in England. Our findings indicate that whilst people recognised they would have future care needs, with associated financial implications, this knowledge did not necessarily translate into actively planning for care or its cost. A key reason that recognition did not translate into action was uncertainty, manifested in three areas: the timescales and trajectory of their dementia and thus need for care; the potential for care needs to change and so negate care planning efforts; and uncertainty over their own capabilities to plan for and access paid-for care, given the perceived complexity of social care and associated financial arrangements. The paper discusses how anticipated regret may affect decision-making and contributes to debates about appropriate professional support for older self-funders with dementia. It suggests the task for those involved in the care of people with dementia is to identify the points and places in the care system where worries about future self-funded care can be addressed, and carers and the people they care for can be prompted and supported to act.