Guarantee Pension Credit, specifically designed to help low-income pensioners, was found to have the highest take-up rate of all benefits reviewed.
Some seven in 10 people who are eligible have submitted a claim for this additional help.
However, those who are failing to claim are missing out on an average of £2,265 per year in extra income.
Conversely, Savings Pension Credit has the lowest take-up rate, with just 45 percent of those who are eligible making a claim.