Parity of esteem establishes that mental and physical health must be treated with equal regard. But a principle only changes behaviour if something measures it. The Mental Health Investment Standard (MHIS) is that measure: a financial target that translates the legal duty into a number each Integrated Care Board (ICB) has to hit, report, and justify if missed.
For London, where five ICBs commission care across 32 boroughs with very different populations and pressures, the standard is the practical mechanism by which parity of esteem is checked, not just declared.
What the Mental Health Investment Standard Requires
The MHIS was introduced in 2016/17 specifically to support the parity of esteem agenda. It requires ICBs (which took over commissioning from Clinical Commissioning Groups in July 2022) to increase their spending on mental health services every financial year. Historically that meant mental health investment had to grow at a faster rate than an ICB’s overall programme funding — not just keep pace with it. More recently, NHS England has framed the requirement as spend rising by at least the ICB’s programme allocation base growth.
That distinction matters. Growing in line with overall NHS funding is a floor, not an aspiration. Growing faster than overall funding was designed to gradually close a funding gap built up over decades in which mental health services were commissioned and resourced as a lower priority than acute and elective physical health care.
From a Legal Duty to a Measurable Target
The MHIS sits on top of an existing legal foundation. The Health and Social Care Act 2012 placed equivalent duties on the Secretary of State to improve both physical and mental health services, and the NHS Constitution commits the health service to treat both "with equal regard". The MHIS is what operationalises that duty at the level individual commissioners actually work at: a spending target with a reporting cycle, rather than a general commitment. Without a target like this, a legal duty to treat two things equally has no obvious mechanism for checking whether that is actually happening year to year.
What Counts as Mental Health Spend
Not every pound spent on services touching mental health counts toward the standard. NHS England defines specific categories, and ICBs are assessed against growth within them. The main categories are:
- Children and young people’s mental health, including eating disorders and mental health support teams in schools
- Perinatal mental health (community-based)
- NHS talking therapies for anxiety and depression
- A&E and ward liaison mental health services
- Early Intervention in Psychosis teams
- Adult community-based mental health crisis care and ambulance response services
Spending on learning disability, autism, and ADHD support is generally excluded from these categories unless there is a co-occurring mental health need. That exclusion is itself a reminder that "mental health" as a funding category is narrower than the everyday meaning of the term — a distinction worth knowing before treating any single spending figure as the whole picture.
How London’s Integrated Care Boards Report Compliance
Compliance is assessed at ICB level and is subject to audit. Each of London’s ICBs is expected to plan toward the MHIS target spend figure set by NHS England, then publish a statement of compliance after the financial year ends — typically alongside its annual report. If spend meets or exceeds the target, the ICB states compliance; if it falls short, it states non-compliance and is expected to explain why.
| Reporting element | Position through 2024/25 | Position from 2025/26 |
|---|---|---|
| External verification | Independent reporting accountant carries out a "reasonable assurance review" of the compliance statement | Independent review phased out; compliance instead confirmed via annual disclosure in the ICB’s annual report and accounts |
| In-year visibility | Expected compliance reported monthly through the Financial Performance Framework | Same monthly reporting mechanism continues |
| Public statement | Published on the ICB’s website, usually alongside the annual report | Same publication expectation continues |
The shift away from independent assurance review is a meaningful change in how rigorously the target is checked, even where the target itself is unchanged.
Why Meeting the Standard Doesn’t Mean True Parity
Funding growth is a necessary condition for parity of esteem, not a sufficient one. An ICB can be fully compliant with the MHIS while patients still face longer waits for mental health treatment than for comparable physical health care, or while service quality and access still vary sharply between boroughs. Parliamentary evidence on this issue is stark: people with serious mental illness die on average around twenty years earlier than the general population, a gap that spending compliance alone does not close.
There is also a live concern, raised by mental health charities, that the standard itself has been softened over time — from requiring investment to outpace overall NHS funding growth toward a definition that may only require mental health spend to keep pace with inflation. If accurate, that would narrow the gap-closing ambition the standard was originally built to deliver, even while ICBs continue to report themselves compliant.
Reading the Standard for What It Is
The Mental Health Investment Standard is the clearest existing mechanism for holding London’s health commissioners to the parity of esteem duty in financial terms. It gives residents, scrutiny committees, and journalists a specific, checkable number rather than a general promise. But it measures inputs — money committed — not outcomes such as waiting times, access rates, or quality of care across boroughs. Anyone assessing whether a London ICB is genuinely delivering parity of esteem should treat MHIS compliance as one data point in that picture, not the whole answer.