The National Institute for Health Research (NIHR) and Marie Curie are the two largest funders of end of life care research in the UK. NIHR and Marie Curie enable and support research at different times of the translational pathway, or by co-funding research. Undertaking a research impact assessment (RIA) on our combined investment is important to make the case for continued investment research and to be accountable to our stakeholders (Morgan Jones and Grant, 2013). RIA is a developing field (Adam et al., 2018). To ensure our approach is relevant, we have involved people with experience of end of life care. We hope that by undertaking this process together, we will gain a better understanding of the research funding landscape and its interdependencies in this area, identify gaps and opportunities, and learn from and support each other. We believe that our project marks the first time that a collaborative RIA of this kind has been undertaken by research funders. We hope that by exchanging, reflecting and sharing our experiences, lessons learned and approach, it will aid discussion, promote shared learning and transparency around funders’ impact assessment processes and may help future collaborative projects. Our learning so far:

• Appropriate oversight, governance and data sharing is a must

• Identify organisational risks up front

• Review organisational factors including resource which may impact on capacity to deliver

• Use of similar tools for data collection enables joint analysis and efficient of data

• collection

• A clear and shared understanding of the project scope is important