Business as usual (BAU)
The outcome expected if current arrangements continue and the proposal is not implemented, used as the benchmark against which every option is compared.
In the Green Book method, business as usual is one of the five elements developed before any options exist, alongside the case for change, the theory of change, the objectives and strategic fit.
It then receives an exemption that no other option gets. An option must not be taken forward to shortlist appraisal if it does not achieve the proposal’s objectives. Business as usual is carried forward regardless, precisely because it is the thing the others are measured against.
Sources
HM Treasury, The Green Book, 2026 edition, paragraph 2.11 for the five elements of rationale and objectives and paragraph 2.16 for the treatment of business as usual at shortlist appraisal.
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