The 10-Year Health Plan offered the best foundation trusts to hold the whole health budget for a defined local population as an IHO.
A small number of IHOs are due to be designated this year and to become operational in 2027.
The 10-Year Health Plan sets out the aim for IHOs to ‘become the norm' over time.
Dr Birju Bartoli, chief executive officer of Northumbria Healthcare, said: ‘It's good news for our patients, staff and local communities for our local area to be given the opportunity to really join up health services in a way the benefits local people.
‘This is just the first step in what will be a long journey and the detail of what this means will emerge as we work closely with local partners to really understand what benefits we can realise for patients, the wider NHS and care services.'
Northumbria and NHFT were among six organisations designated as advanced foundation trusts in May.
NHFT said its initial development work will focus on children and young people and mental health, learning disability and autism services, with opportunities to expand over time.
Angela Hillery, chief executive of NHFT, said: ‘This is not about one organisation doing more. It is about all of us working together differently, bringing our collective experience, skills and insight to support people earlier and in a more joined-up way and so that people experience more joined-up, responsive and compassionate care.
‘We know that people experience services as a whole, not as separate organisations. This gives us an opportunity to design care that feels more connected and responsive.'
Toby Sanders, chief executive of Northamptonshire ICB, said: ‘This opportunity allows us to explore new ways of organising services around people's needs, with a stronger focus on prevention, reducing inequalities and improving population health. The overall aim is for people to experience care as one journey, not as separate organisations.
‘The ICB remains committed to working alongside NHFT, primary care, local authorities, voluntary sector partners and local communities as we develop the next phase together.'
