The one thing some people think is worse than cheating on your wife

A Finder survey of 1096 respondents revealed one in five Australians - about 4.2 million people - think lying to your partner about finances is worse than physically cheating.

Leading this trend were Baby Boomers, making up 23 per cent of people concerned with financial fibs in a relationship, compared with 22 per cent of millennials, 21 per cent of gen X, and 18 per cent of gen Z.

"Purposefully hiding information about money is a major red flag in relationships, especially when couples share finances," Personal finance expert Sarah Megginson said.

"Financial lies can be quite destructive and leave people feeling betrayed and untrusting."

Motives for lying about money may include embarrassment over a secret debt or an addiction that's gotten out of control.

It may also be about a secret account your partner hasn't told you about, that acts as a financial safety net for them if the relationship ends.

Finder's research found 79 per cent of Australians say that having an affair is worse than being dishonest about your finances.

Sarah said while conversations about money are difficult, they're important to have. She encouraged people to have open and honest conversations with their partner as often as possible.

"If you're hiding something, consider coming clean sooner than later. The longer it goes on, the bigger the problem can grow and the more elaborate your lies are likely to become," she said.

"Financial trust is really crucial in a relationship, so it's ideal if you can talk openly about money and get on the same page, and ideally support each other to reach financial goals together."

Need to talk?

Worried about being taken advantage of or can't leave a relationship because of financial issues?

Both parties can access the money. Because you both have complete access to the account, either person can spend the money. This is why it's important to open a joint account with someone you trust.

Overdraft facility. If your joint account has an overdraft facility available, it means you can spend more money than what's available in the account, forcing your balance to go into the negative. Even if you didn't spend the money, you're both liable to repay the money and your credit score may be affected if you can't.

Division of funds if you separate. If you separate from your partner, dividing the funds in the joint account can be a messy, awkward task. Also, there's nothing to stop the other person from clearing out the account entirely.

Privacy. Everyone whose name is on the account will have easy access to the account online and will be able to see the transaction history of all account holders.