Women drivers could see insurance premiums increase by around 25% as new laws come into force that ban setting prices according to gender.
Researchers believe it could force nearly a quarter of women drivers to give up driving altogether.
The European Court of Justice ruling follows a 10-year legal battle against the proposals by insurers.
It is not confined to car insurance but also covers pensions and life insurance.
Car insurance premiums could increase for young female drivers by an average of around £300 a year.
Those aged between 31 and 35 are also likely to be hit with a rise of around 10%, or £53 a year, according to research from comparison website Confused.com.
Michael Ossei, personal finance expert at price comparison website uSwitch, told Sky News: "What we have found is young women between 18 to 25 years old will be heavily affected by the change.
"What that means from our research (is that) 24% will be taken off the road, not able to drive, while a further 11% say they will have to sell their cars."
Men reaching retirement could also be hard-hit with annuities possibly decreasing by up to 13% a year, while women may see their life insurance policies increase by 16%.
Currently, men usually get a higher pension income than women because, on average, they die younger.
The Government is strongly opposed to the change.
Transport Minister Stephen Hammond told Sky News it was unnecessary and that they were working to manage the impact.
"One of the reasons we are against it (is that) the basic principles of insurance previously has been insurance based on risked rather than just gender-based."
The court ruling is an attempt to end discrimination and to bring about equality between men and women - but it is a decision that will come at a price for many.