The 2026 Green Book update: is your business case ready for what has changed?

Sewell Advisory Senior Consultant Anna Matta is an experienced Better Business Cases Practitioner, having secured significant capital funding for public sector infrastructure business cases in the past few years. 

Here, she reflects on the latest HM Treasury Green Book update and what it means for organisations developing business cases today. 

If you are still using the Green Book the way you did in 2025, you may already be behind. 

The February 2026 update isn’t just a technical refresh – it reshapes how public investment decisions will be made for years to come. 

What’s striking isn’t any single change. It is the cumulative effect. The bar for projects to secure funding has been raised – around place-based impacts, distribution of benefits, uncertainty and credibility. More projects may fall short if they are not attuned to this new guidance. 

A few key shifts: 

• ‘Who benefits and where?’ now matters as much as ‘Is it value for money?’ Place-based benefits aren’t a nice-to-have any more, they’re a core requirement. Value for money still matters, but it’s now part of a wider judgement about local impact, inequalities, and alignment with place-based priorities. 

• Weak scenarios or sensitivity analysis will hold back otherwise good projects from gaining approval, and your appraisal needs to demonstrate it can stand up to uncertainty and risk.   

• Social value can’t just be asserted. General statements or ‘nice-sounding’ benefits won’t be enough anymore – the proposed impact should be specific to the project and population affected and use a recognised analysis to quantify the measurable benefits.   

• Appraisal must follow a chain of responsibility. Your business case must align with higher-level local and national strategies as well as your own policy and portfolio approaches – supported by proportionate evidence to justify the preferred option.    

For organisations preparing major investment proposals, the question is no longer ‘Is this a good project?’ but ‘will this case withstand this new level of scrutiny?’ 

This summary captures only the headline shifts, but even these signal a very different landscape for organisations building proposals in 2026 and beyond. But the direction is clear: business cases need to be sharper, more place-focused, more disciplined, and more credible. 

Sewell Advisory has a multi-disciplinary team of estates experts ready to support you to create HM Treasury-aligned business cases to fully understand your case for change, conduct a robust options appraisal and secure any required funding for your service or capital transformation projects and programmes.