Campaigners are pressing for concessions for the 300,000 'fiftysomething' women who face years of delay in receiving their State pension.
The third reading of the Pensions Bill is due in October and charities and lobby groups want a promise of help for the women in their 50s who will be affected most by the new law.
At the same time, other women, also in their 50s, say they have been penalised by the pensions system because they paid the reduced rate of National Insurance Contributions (NICs), commonly known as the married woman's stamp.
They are calling on Pensions Minister Steve Webb to look again at their plight as the Government overhauls the State pension.
Despite reforms that will help future generations of women, and also specific concessions made in 2008 by the Labour government to try to address the problem of the reduced stamp, the situation for most women in this group has been ignored.
Campaigners say they are the 'forgotten generation' and are calling on the Government to tackle their plight. More than four million women paid the married woman's stamp at some time. It was scrapped in 1977, but those already paying it could continue to do so.
The stamp was a discounted rate of Class 1 NICs and working married women were encouraged to sign up as a way of saving money.
But though most understood that this meant they forfeited the right to any unemployment or maternity benefits, the implications for their retirement were often not spelled out to them.
It means that these women will never get a State pension in their own right. Instead, they will be paid 60 per cent of their husband's basic State pension (up to £61.20 a week in 2011/12) based on his NICs, but only when he reaches State pension age at 65, or 66 from 2020.
In most cases their loss, which could run into tens of thousands of pounds over the course of the average retirement, far outweighs any gains they made by paying a lower NIC rate.
More... New state pension age: when will you retire?Campaigners at charity Age UK say it is worrying that in many cases it was not fully explained to these women the consequences of paying lower National Insurance Contributions for their State pension allowance.
They say that State pension reforms have passed these women by and in many cases they are disadvantaged.'
Changes made in 2008 have allowed some of these women to buy back up to six years of NICs. However, only women with at least 20 years of existing full-rate NICs and those who will reach State pension age before April 5, 2015 are eligible.
It means those who would benefit most were left out in the cold. Among them is June Richards, 58, who began paying the married woman's stamp at 21. Like millions of other women, June, a human resources manager who was married in 1973, says she was encouraged to sign up.
There was no specific discussion about how her pension rights would be affected, but it has turned out to be a terrible financial decision.
June, who does not have children, has worked continuously for almost 30 years, yet she will get no State pension in her own right from her reduced-rate NICs.
She estimates her total net loss will be more than £25,000, depending on when she retires. This is because she will get only 60 per cent of the basic State pension based on the NICs of her husband, Stephen, 58, an interior designer – a loss of £41 a week, or £2,132 a year. If June lives to 89, it equates to a loss of more than £50,000. But she thinks the savings made on paying the reduced NIC rate early in her career probably add up to less than £25,000.
'It was effectively acknowledged that the system was unfair when the reduced stamp was axed in 1977,' June says. 'I do not think the issue should be swept under the carpet. It seems only fair to look at ways of crediting women like me, or allowing us to buy back lost years.'
Webb was hugely supportive of women who paid the reduced stamp when he was in opposition as Liberal Democrat Work and Pensions spokesman. But now he says that nothing further can be done as this would not be fair to those who have paid full NICs.
One of the main criticisms of the system is the inequalities between groups of women.
For example, mothers and carers who did not opt for the reduced rate can be given up to 16 years of NIC credits under the home responsibilities scheme if they were out of the workplace.
Yet those paying the reduced rate, such as June, or those working part time or on low incomes who did not earn enough to pay full Class 1 NIC rates, get no credits.
Divorced and widowed women who paid the reduced stamp can qualify or improve their State pension based on their husband's NIC record, provided that they do not remarry before State pension age.
Double whammy: Company scheme payouts at risk
Some of the women facing a two-year delay in receiving their State pension under the Pensions Bill face a double whammy – with a loss on their company pension.
Many schemes operate a bridging arrangement that pays the equivalent of the State pension on top of the company payment until the member reaches State pension age.
At that point the cash is deducted as it is assumed the State benefit is being paid.
At Marks & Spencer, for example, workers can retire at 60. However, women will find the equivalent of the State pension is cut from their company pension at 64, even though under the new Pension Bill rules they will not receive the State cash until they are 65, or even 66 in some cases.
The Government is considering whether an amendment to the legislation is needed. Catherine Cunningham, policy adviser at the National Association of Pension Funds, says: 'Company schemes are applying bridging pensions differently. Some will state that the money is reduced at ''State pension age'' while others may specify an exact age, such as 64, which is where people will lose out.'
MPs debated all issues surrounding the controversial Pensions Bill last month, including issues for the thousands of women aged 56 and 57 who will have to wait up to an extra two years to receive their State pension. The third and final reading of the Bill is expected in October.
It is hoped MPs will try to thrash out a compromise solution to help them. This could involve delaying the increase in State pension age to help this group or compensating them in some way.