As a response to the ageing population, the United Kingdom (UK) government, like many others, has increased the State Pension Age. This has involved equalising women's State Pension Age with men's, raising it from 60 to 65, with further increases already underway. It has been argued that a key issue with how this change has been implemented is the lack of notice the government gave to the women affected, impacting on their ability to plan for retirement. So far, there has been very little research exploring inequalities in awareness of these developments and, in particular, considering whether women of particular socio-economic backgrounds are less likely to know about the changes. This has implications for potentially further widening inequalities in old age. In this paper we analyse data from the English Longitudinal Study of Ageing. We consider the role of cognitive ability in mediating the relationship between socio-economic background and awareness, given recent debates on deficiencies in financial literacy. We find that socio-economic inequalities exist, especially with respect to labour force status, occupation and education. We also find that cognitive ability, especially numeracy, mediates a sizeable proportion of the relationship. These findings have important implications in terms of implementing future policy changes and awareness campaigns to help mitigate the possibility that they will further entrench inequalities in older age.