The findings were detailed in a blog authored by the ICO's Director of FOI, Warren Seddon, which also found that smaller NHS Trusts performed better than larger Trusts.
According to the blog, the rate of compliance with the statutory deadline ranged from 10% to 100%, and the average compliance rate across each NHS trust was 82%.
Smaller NHS trusts appeared to perform better than larger trusts, with small trusts (less than 5,000 employees) having an average compliance rate of 92% and a backlog of three requests.
Large trusts (with over 10,000 employees)meanwhile reported an average compliance rate of 71%, alongside a backlog of 86 requests.
Based on the sample and the complaints closed during the 2024/25 financial year, the watchdog found that only around 0.4% of FOI requests received by NHS trusts in England result in a complaint being dealt with by the ICO.
This suggested "that on the whole, NHS trusts are doing pretty well", Seddon wrote.
However, four trusts were hit with regulatory action, as a result of the review.
Nottingham University Hospitals NHS Trust was subject to an enforcement notice due to a "significantly low compliance rate" of 17% and almost 200 requests over a year old.
Manchester University Hospitals NHS Trust was hit with a warning over shortcomings in relation to FOI compliance, however the ICO said steady improvements are being made, resulting in a practice recommendation.
Greater Manchester Mental Health Trust meanwhile showed progress following a 2022 independent review, but, between April 2024 and May 2025, was the subject of six complaints about delayed FOI responses.
The trust admitted to having backlog of 20 requests, including five over nine months old in the final financial quarter of 2024/25, resulting in a practice recommendation.
Guys & St Thomas NHS Trust was also handed a practice recommendations after the ICO uncovered a "significant backlog" of FOI requests, resulting in a compliance rate of just 33% in March 2024.
This has since improved to 61% in May 2025 and the Trust is in communications with the ICO on ways to further improve its resilience and future compliance, the report added.
In light of the ICO's review, the watchdog encouraged all trusts to:
- Put thorough processes in place for FOI request handling across service areas with a minimal impact on frontline staff where possible.
- Establish a network of contacts and dedicated FOI champions considering frequent movement of staff in the healthcare environment.
- Raise awareness to improve the understanding of how FOI operates in relation to requests from companies seeking commercial information.
- Publish commonly requested information such as that relating to agency staff, recruitment, prescribing, waiting lists and in-sourcing/out-sourcing.
- Make sure senior leaders have regular sight of their organisation’s performance against its statutory duties so they can take early action when needed.
The ICO said it took a wider look into how NHS Trusts across England are complying with FOI obligations, in an attempt to identify both strengths and areas for improvement.
The study looked at 31 trusts, or around 15% of NHS trusts across England, varying in size and location for its review. The ICO also visited eight of the trusts to hear directly from staff about their experiences, challenges, and successes.
Commenting on next steps, Warren Seddon said: "We face record levels of complaints and significant pressure on our resources, but we will continue to focus as much as possible on addressing systemic issues within public sector bodies."
He later added: "Beyond this, we continue to monitor and engage with a wide range of sectors to ensure strong compliance with FOI legislation and where necessary, we will take action to drive improvement.
“For example, we recently issued practice recommendations to both the Attorney General’s Office and the Cabinet Office, highlighting areas for development and offering support to implement change.
"We remain committed to supporting public bodies in meeting their FOI obligations, even in the face of growing pressures.”
Adam Carey