David 'Kochie' Koch exposes the shameful money mistake many Aussies are making when it comes to their partners

Finance guru and former Sunrise host David Koch says too many Australians are hiding their bad spending habits from partners.

He has spoken out after new Compare the Market data showed one in three Aussies had lied to their partner about their finances as the cost-of-living crisis puts strain on relationships.

This is especially so for younger couples struggling with surging rents or mortgage repayments. 

'I've been talking about finances for decades, and one thing that shocks a lot of people I speak to is how many of us keep financial secrets from loved ones,' Kochie told Daily Mail Australia.

'There's a real push right now for people to save and stretch their money further and I'd hedge a bet that many of us feel shame or guilt for splashing on that morning coffee, buying a sneaky takeaway meal at lunch or even splurging on a new outfit.

'But being dishonest with our partners is an unhealthy habit that can have serious consequences if issues are left to snowball.'

An alarming one in five Australians are also lying about a gambling addiction, based on the survey of more than 1,000 Australian adults in June.

Koch, who is now Compare the Market's research director, said gambling debts could stop a couple qualifying for a home loan, with banks having access to a consumer's spending habits and debts.

'Betting, gaming and excessive spending on lotteries can also hurt your chances of getting a home loan as many lenders see this as risky spending that could mean you're not able to service a loan in future,' he said.  

A similar proportion of deceitful Aussies are also concealing their true debt levels from their partners. 

When it came to lying overall, four in 10 Aussies told fibs about what they had spent their money on.

More than a quarter lied about spending money on things like coffee and takeaway food while a similar number lied about splurging out on clothes.

One in eight Australians were also lying about how much they earned. 

Koch said struggling Australians needed to get over the shame of being in debt or having too many expenses.

'There can be a real shame around money and some people try to protect their loved ones by pretending their finances are in a better shape than they really are,' he said.

'I don't know where this mentality came from, but we need to do a better job of reaching out for help if we need it.'

Lying could also be particularly detrimental if a couple was saving up for something like a mortgage deposit or a new car.

'If you have money problems, is it fair to hide them from your partner, especially if you are pooling money for a house deposit or other shared goal?'

The complications could get worse for parents raising children.

'If you have a lot of debt, and you have a partner or children that are financially dependent on you, you could find yourself having to make some very difficult and stressful choices that shouldn’t be dealt with alone,' Koch said.

The Reserve Bank last month left interest rates on hold at a 12-year high of 4.35 per cent but it hinted at another possible increase.

That's because inflation in the year to May rose by 4 per cent, putting it further above the RBA's 2 to 3 per cent target.

While rates haven't risen since November, home borrowers have copped the most aggressive rate rises since the late 1980s, causing a 68 per cent surge in monthly variable mortgage payments.

Renters are doing it even tougher, with Australia suffering from a housing shortage.

Electricity bills are also rising at a rate that's higher than overall inflation, as wages barely keep pace with the consumer price index.