Prudential has called for women over the age of 55 to check whether they will receive the full State Pension.
While pension reform has made strides for a fairer system, the Department of Work and Pensions (DWP) has said a quarter of women retiring this year will not be eligible to receive the full amount.
Deirdre Flood, retirement expert at Prudential said: "The closure of the pensions gender gap is happening too slowly."
Research from Prudential shows women are twice as likely as men to rely on the state pension in retirement - with one fifth of women having no personal pension compared with only 9% of men.
Many women will miss out because the previous system made it difficult for carers and those with inconsistent employment histories to accrue benefits.
In addition, a third of women over-estimate the State Pension and 10% do not know how much it is worth.
Prudential's research also shows women lag behind men in building up the State Second Pension Credit. According to the DWP women won't catch up to men until 2040.
And less than a third (31%) of women planning to retire this year believe they will have enough income to retire in comfort. This compared to nearly half (45%) of men.
Flood added: "Recent legislative changes have made the pension system fairer for women. However, many women who are over the age of 55 will fail to qualify for the full Basic State Pension as they have spent much of their working lives earning money under more rigid accrual rules.
"The closure of the pensions gender gap is happening much too slowly. Women need to take control of their finances. However, there are some steps that they can take to improve their situations in retirement.
"Topping up National Insurance contributions, paying into company pension schemes where possible and consulting a financial adviser about their retirement provision, will all help to ensure a more comfortable retirement."
Recent research from Halifax has also revealed men are still making better provision for their retirement than women with 49% of men saving adequately compared with 42% of women.
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