ICB clusters and mergers: what you need to know
Key points
To meet the 50 per cent cost reductions required by NHS England and harness economies of scale, the majority of integrated care boards have agreed ‘clustering’ arrangements, with two or more ICBs working together across a larger footprint but remaining separate organisations legally.
Current clustering arrangements will not automatically become the new boundaries for merged ICBs. Any merger or change in ICB boundaries is subject to ministerial approval, but clustered ICBs might explore mergers to function on their reduced costs.
Across the 42 ICBs, clusters have been agreed in the Midlands, London, East of England, South East and South West. No clustering arrangements have been developed in the North East and Yorkshire and North West regions.
While clusters will not automatically merge, those ICB clusters that receive ministerial approval will prepare to legally merge into new organisations from April 2026, with support from NHS England.
ICBs are committed to delivering the efficiencies needed to reduce duplication across the health and care system. The centre must support them to deliver these changes as safely and effectively as possible by ensuring a clear and consistent approach.
The transition for some ICBs to cluster arrangements and then mergers should support and not hinder their role as strategic commissioners and their focus on delivering the 10 Year Health Plan.
Overview
In March 2025, NHS England announced that integrated care boards (ICBs) should reduce their running and programme costs by 50 per cent to become more efficient and reduce duplication, by December 2025. Alongside this, NHS trusts and foundation trusts have been asked to reduce their growth in corporate costs and NHS England will be merged back into the Department of Health and Social Care.
The scale of the cost reductions means that most ICBs cannot exist within their current population size and function on a cost basis of £19 per head of population. Over the past few months, most ICBs have agreed clustering arrangements to harness economies of scale, with potential mergers from April 2026.
Clustering describes two or more ICBs working together across a larger footprint but remaining separate organisations legally. This could include the establishment of joint committees, forming combined teams or joint senior appointments. This is not the first time the NHS has established clustering arrangements. Previous commissioning structures, such as primary care trusts (PCTs) and clinical commissioning groups (CCGs) developed clustering arrangements ahead of legislative changes.
Will ICBs merge following clustering arrangements?
Clustered ICBs might explore mergers to continue functioning on their reduced costs. There are different possible approaches to mergers. For example, abolishing the relevant ICBs and establishing a new ICB. However, current clustering arrangements will not automatically become the new boundaries for merged ICBs. Any merger or change in ICB boundaries is subject to ministerial approval.
A key factor for decision-making around ICB boundaries will be the development of strategic authorities. As described in the 10 Year Health Plan, the government intends to ‘make ICBs co-terminous with strategic authorities by the end of the plan wherever feasibly possible’. However, the establishment of new strategic authorities and the implementation of local government reform is on a much longer timeframe than ICB reorganisation. ICBs are expected to function on their reduced costs from 1 April 2026. New mayoral elections for devolution priority areas are expected in May 2026 and full coverage across England is only expected by the end of parliament.
Each area will need to balance the opportunity to align with strategic authority and local government boundaries where possible with a range of other considerations. This will include the implications of a merger on clinical and patient flows, NHS commissioner/provider relationships, staff, quality and finance.
Which clusters have formed?
Across the 42 ICBs, 15 clusters have been agreed and 11 ICBs are not clustering (see the appendix). The clusters were developed on a regional basis.
There have been no clustering arrangements developed so far in the North East and Yorkshire (four ICBs) and North West (three ICBs) regions.
Midlands
In the Midlands, 11 ICBs have agreed the following five clusters:
- Leicester, Leicestershire and Rutland with Northamptonshire
- Derbyshire, with Nottinghamshire and Lincolnshire
- Birmingham and Solihull with Black Country
- Staffordshire and Stoke-on-Trent with Shropshire, Telford and Wrekin
- Coventry and Warwickshire, with Herefordshire and Worcestershire
London
In London, a cluster has been established between North Central and North West London ICBs.
East of England
In the East of England, six ICBs are expected to reduce to three clusters. Norfolk and Waveney ICB and Suffolk and North East Essex ICB have established themselves as a cluster. And Cambridgeshire and Peterborough ICB, Bedfordshire, Luton and Milton Keynes ICB and Hertfordshire and West Essex ICB are working together as a three-way cluster.
Essex areas of Suffolk and North East Essex and Hertfordshire and West Essex ICBs are aligning with Mid and South Essex ICB, potentially establishing a Greater Essex ICB in the future.
South East
In the South East, there will be four clusters across the six ICBs. Surrey and Sussex ICBs have formed a cluster. Frimley ICB is currently clustering with Buckinghamshire, Oxfordshire and Berkshire West (BOB) and some of its geography aligned to the Surrey and Sussex cluster, and Hampshire and the Isle of Wight ICB, according to local government boundaries.
Over time, it is likely that BOB will become the new Thames Valley ICB to better align with a potential Thames Valley mayoral strategic authority, which is currently being discussed.
South West
In the South West, three clusters of ICBs have been agreed:
- Cornwall and the Isles of Scilly with Devon
- Gloucestershire with Bristol, North Somerset and South Gloucestershire
- Dorset with Somerset and Bath, North East Somerset, Swindon and Wiltshire
What do these changes mean?
In the short term, ICBs are focused on restructuring their organisations and implementing new governance arrangements and ways of working as clusters. This will support the delivery of their 50 per cent cost reductions by April 2026. While clusters will not automatically merge, those ICB clusters that receive ministerial approval will prepare to legally merge into new organisations from April 2026, with support from NHS England. Any future round of mergers would take place in April 2027 and beyond. As described above, both the timeline for a merger and the boundaries of new merged ICBs will depend on a combination of factors, including changes to local government and devolution structures.
ICBs are committed to delivering the efficiencies needed to reduce duplication across the health and care system. The centre must support them to deliver these changes as safely and effectively as possible by ensuring a clear and consistent approach. We know how much structural organisational change can distract from a focus on improving people’s outcomes and experience of care and can impact leaders’ ability to engage with partners.
The transition for some ICBs to cluster arrangements and then mergers should support and not hinder their role as strategic commissioners and their focus on delivering the 10 Year Health Plan. Larger populations across ICBs will have implications for their arrangements at place andneighbourhood as well as how they best engage with and work with local communities. ICBs will be carefully examining how to best make use of the £19 per head to deliver strategic commissioning and the transformation required.
The NHS Confederation’s ICS Network will continue to provide opportunities for ICBs to connect, share learning and influence national policymaking as they undergo these changes. We will also be supporting members through our Strategic Commissioning Forum and our programme of work on health and devolution.
