Nearly one in five adults have been a victim of "financial abuse" while in a relationship with a partner - equating to more than nine million people across the country - a report has found.
Some 18% of people surveyed for the Co-operative Bank and domestic violence charity Refuge said they had experienced some form of financial abuse in a past or current relationship, with money being used as a weapon to exert control over them.
The abuse could include anything from being forced to hand over their monthly wages to a partner, or not being allowed to have their own bank account, to their partner stopping or interfering with them going to work. Women were more likely to have been victims than men.
Refuge said that financial abuse is a form of domestic violence, often taking place alongside other forms of abuse, such as physical, psychological and emotional abuse.
It said domestic violence happens when someone uses their behaviour to control, undermine and obtain power over another person.
People who carry out financial abuse aim to control someone else's money or exploit or sabotage their finances.
Common signs of financial abuse include someone's partner using money as a means of manipulation, or taking their cash without permission, or putting debts in their name when the victim is afraid to say no. Victims may also need to ask permission to spend their own money.
Describing how financial abuse can take place, Sandra Horley, chief executive of Refuge, said: "Some women are forced to hand over their wages or benefits to their partner every month.
"Others are prevented from going out to work or completing their education. Many victims are forced to provide receipts, accounting for every single penny they spend or are given such ridiculously small 'allowances' they can't afford to buy food for themselves and their children.
"Some are forced into debt, shackled to a past relationship through a churn of constant bills and repayments."
Some victims reported being left with a poor credit history or were struggling financially as a result of the abuse.
The report said that if the findings were projected across the UK, this would equate to 9.2 million adults suffering or having suffered financial abuse in an intimate relationship.
More than one third (36%) of people who had suffered financial abuse had a household income of between £20,001 and £50,000. One quarter (25%) had a household income of more than £50,000.
One in 10 (10%) victims had a household income of up to £10,000, while one in five (20%) had a household income between £10,001 and £20,000. The remaining 9% preferred not to give details of their income.
Just over a third of those reporting financial abuse (35%) were experiencing it within their current relationship, while three-quarters (74%) of victims experienced it in a past relationship. Some people experienced financial abuse both in a past relationship and in a current relationship.
One in three (34%) victims of financial abuse said they had told no one about it. Two-thirds (67%) of those who had kept silent were women.
The study of more than 4,000 adults found that in 60% of cases of financial abuse reported, the victims were women.
Women were also more likely to suffer financial abuse for a longer period. More than three-quarters (78%) of female victims said the abuse they suffered went on for more than five years, compared with 23% of male victims who said this.
Financial abuse against women was more likely to start at key life stages, such as moving in with a partner, getting married or starting a family, the research found.
This form of abuse rarely happened in isolation - with 82% of victims also having experienced other forms of abuse in their relationship, according to the findings.
The report highlighted the launch of a campaign called "my money, my life", which aims to raise awareness of the scale of financial abuse taking place and encourage greater support for victims.
It called for the development of a code of practice for financial institutions so that there is a consistent response to financial abuse.
The Co-op Bank said it is committed to working with the industry to develop guidance on how to recognise signs of financial abuse.
Laura Carstensen, chairwoman of the Co-operative Bank's values and ethics committee, said: "The impact of this kind of coercive control where money is used as a weapon within an intimate relationship is not yet fully understood."