ity in relation to the development and maintenance of the TFD and TFE since the former’s inception in 2015 to 2023. We also considered perceived benefits in relation to time-saved in this timeframe as a result of using these products within Bristol City Council and schools that use the TFE. For benefits, the CBA exclusively considers time saved on tasks attributable to TFD or TFE. Effectiveness benefits, which based on qualitative research are the main benefits, could not be accounted for due to challenges in obtaining outcome data and the unreliability of attributing such benefits to the TFD / TFE. We opted to concentrate on efficiency for a more robust calculation, acknowledging it represents only a portion of the overall benefits. Valuation method The TFD and TFE surveys, and interviews with practitioners in Bristol, asked about time saved as a result of using these tools. We calculated an average time saved per user based on the answers received. This was then multiplied by the number of active users to determine the total hours saved. We then derived a monetary value of this by approximating hourly costs of different users using Bristol City Council operational salary bandings and other public pay scales. In turn, we totalled costs since the TFD’s development, including team support and maintenance costs. Cost and benefits in different years were adjusted to 2023 values using the Green Book social time preference rate (STPR) of 3.5%, and an inflation deflator. Social Finance Limited +44 (0) 20 7770 6836 87 Vauxhall Walk, London SE11 5HJ socialfinance.org.uk 50 To arrive at a final cost-benefit figure, we modelled various scenarios to address uncertainty in our estimation of time saved. We present the base scenario here and include additional scenarios in Appendix 9