In our evidence session on 17th November 2021, we observed that the cost tracker had supported Parliamentary scrutiny of departments and enabled us to hold government to account.9 We have found the model used in the cost tracker very useful, and it has helped in the ongoing exercise of monitoring COVID-19 spending.10 We asked HM Treasury whether it planned to use a similar model to the cost tracker in future to track other areas of spending. HM Treasury told us that it was still looking at whether it would 5 The COVID-19 cost tracker, available at: COVID-19 cost tracker - National Audit Office (NAO) 6 Committee of Public Accounts, COVID-19 Cost Tracker Update, Twelfth Report of Session 2021–22, HC173, 19 July 2021 7 HM Treasury, Government response to the Committee of Public Accounts on the Twelfth and Seventeenth to the Twenty-First Reports from Session 2021–22, CP 583, 9 December 2021 8 Letter from Tom Scholar, Permanent Secretary, HM Treasury, to Dame Meg Hillier MP, Monitoring the cost of cross-government programmes, 23 December 2021 9 Q 13 10 Qq 1, 56–58 COVID-19 cost tracker update 9 use a model similar to the cost tracker to monitor other areas of thematic spend, such as the transition towards a net zero economy. HM Treasury said that the nature of the COVID-19 pandemic and its impact on the economy and public finances, meant that it was easier to identify the public spending implications of it than would be the case in other situations. For example, it told us that the banking crisis some 12 years ago was “also an enormous shock” and that it was difficult to attribute particular fiscal pressures to the banking crisis because it required disentangling lost tax revenue and additional public spending. It told us that most net zero related spending will also be designed to achieve other objectives, so it would be difficult to determine what is being spent on one objective or another. HM Treasury recognised, however, that it needed to work out the best way to ens