Do minimum
The option that just achieves the objectives and goes no further, carried on the shortlist to test whether more ambitious options are worth their additional cost.
In the Green Book method, a shortlist should generally contain around five options, and do minimum is one of the standard five. The others are business as usual, a preferred way forward, a more ambitious version of it and a less ambitious version. Five is not arbitrary: the guidance states that a range of that size means decision makers are presented with genuine choices rather than a single pre-determined outcome.
Do minimum has to meet the objectives and the critical success factors, like every option except business as usual. What distinguishes it is that it stops there. Its function is comparative. If a more ambitious option costs more and the additional benefit cannot be demonstrated against the do minimum, the difference is what the guidance calls gold plating.
The less ambitious way forward may be dropped from the shortlist where the preferred way forward is itself the do minimum, since the two would then be the same option described twice.
Sources
HM Treasury, The Green Book, 2026 edition, paragraph 5.17 on shortlist size and paragraph 5.18 for the five options a shortlist should typically contain, including the definition of do minimum and the reference to gold plating.
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