The Financial Ombudsman identified a quarter of customers who made complaints last year as being at risk, compared to 10% the previous year.
Figures for 2025/26 show it recorded 52,900 customers as being at risk, compared to 32,000 in 2024/25 when there was a higher overall number of cases due to the impact of the car finance scandal.
The Ombudsman says this increase follows training and other work to help identify vulnerabilities.
It comes after the Financial Conduct Authority found last year that many vulnerable customers did not identify themselves as such, putting the onus on firms and regulators to do more to ensure they do not slip through the net.
FCA research revealed that only four in 10 vulnerable customers disclosed their needs to their financial services provider.
However, research shows that those who are open tend to have better experiences.
Three quarters, or 74%, of vulnerable customers who told their company about their circumstances said staff asked the right questions to understand their situation, 57% said their company “cared,” and 58% said their company took action to provide the support they needed.
