The employment rate for men aged 65 rose by 10 percentage points, and by 13 percentage points for women at the same age.
The research has therefore evidenced somewhat of a disparity between lower earners and their higher-earning counterparts.
Jonathan Cribb, associate director at the IFS, said: “The sharp increases in employment have come in particular from those in poorer areas, and for those who have lower levels of education, suggesting that without a state pension they cannot afford to retire.”
The research estimated an additional 5,000 65-year-olds are now unemployed and looking for work as a direct result of the state pension age increase.
Indeed, some 25,000 individuals are out of work due to long-term health reasons, rather than retirement, also as a result of the state pension age rising from 65 to 66.