Legacy systems are problematic for two main reasons. Firstly, they are a significant driver of cost, comprising around one-third of government’s technology estate but representing almost half of its costs.30 This may not include the excess costs that arise from people having to work manually around cumbersome, old systems and poor-quality data from fragmented data sources.31 Secondly, legacy systems are an impediment to being able to gather better cost data as data extraction often requires manual effort as repeated point-in-time exercises.32 The Cabinet Office recognises the need for Permanent Secretaries to have a good understanding of their legacy systems. The Department for Science, Innovation and Technology (DSIT) has baselined government legacy systems and reviewed departmental bids for funding in the 2025 Spending Review to mitigate the risks such systems pose. It told us that although there has been a step- change in how senior leaders are thinking about their legacy systems, there were not as many bids for funding as expected.33