The report, revealed exclusively to PRWeek by think tank nfpSynergy, says charities are failing to take into account changes in society in their campaigning, most notably the UK's ageing population.
According to report co-author nfpSynergy head Joe Saxton, as people live longer, they may be more inclined to give through legacies.
It also presents the voluntary sector with an increasingly active group of potential volunteers and staffers. Saxton said: 'The elderly are increasingly important, and at the moment are not being properly targeted.'
The report also highlights the increases in student debt, making people less inclined to give during their 20s. Saxton argues that charities need to better target people when they are of school age, 'to soften them up for when they are in a position to give in later life'.