When Wendy*, a stay-at-home mum, unintentionally found out that her husband, a banker, got a big pay raise, it made her realise that throughout their entire 10-year marriage, he had never once shared details of his income, bonuses or investments.

When she broached the subject to her husband about wanting to celebrate his work success, he evaded talk about his finances, jokingly suggesting that she was a gold digger.

Then there's Kevin* and Cindy*, a couple in their late 30s, who had worked out an arrangement where Kevin, who works in the retail sector, would take care of most of the family's expenses.

Cindy felt that the man of the house should look after the family, like her father used to, even though she had a job in the IT industry.

Kevin gradually became resentful that his wife wasn't sharing the financial burden, and he became suspicious when he found out she had a secret savings account which she kept for her own use.

He never confronted her about it and the problem was allowed to fester. Eventually, the relationship soured and they separated.

Bryan*, 40, a business development manager, and Dana*, 39, a finance executive, have open discussions about their incomes, and who should contribute how much towards their household expenses, from car instalments to phone bills.

They have a joint bank account to pay for big ticket items like shares, holidays and property.

When it comes to marriage, experts say that being upfront with financial matters, like Bryan and Dana, is a win-win situation.

It's often not about the money - but the keeping of these secrets that erodes trust, says Yash Mishra, head of private client services of Ipac Singapore.

"(Keeping secrets) builds distrust. Even a small lie can lead to bigger lies, such as not telling your partner you dipped into the joint account to lend money to your family or friends. If the impact of these cumulative white lies are severe enough, it could break down the marriage."

So, what financial matters should you always share with your spouse? Experts say:

Your Incomes

Some spouses under-declare their income to their partners and secretly stash the extra money into a "private expense" account.

Men, in particular, tend to be secretive about their income.

"Perhaps they lack assurance that their wives can be trusted with financial matters or they're afraid their wives might overspend if they know there is extra cash, especially if the wife has exhibited such behaviour in the past," says Ng Ai Ling, executive director of Reach community services society.

"It could also be because they have mistakenly associated money with a sense of being in charge or control in a marriage, or they could be hiding a secret from their spouses, for example, an addiction or an affair."

Why it shouldn't be a secret:

"When you're able to tell your spouse how much you earn and can willingly commit a large portion of it to the family, it shows your trust and concern for the family," says Raymond Wee, associate director of Financial Alliance.

Money No Enough

Sandy*, a civil servant in her 40s, was puzzled as to why her husband, also a civil servant, kept putting off purchases like going on a holiday and buying home appliances, saying that he could not afford them.

She later discovered that he had put almost all their savings into a non-mainstream investment, which they could not back out of without hiring a lawyer.

She was so incensed she cancelled their joint account out of fear that he would make another impulsive decision with the money.

Raymond says that when there is a shortage of money to pay for things, it is the usually the men who find it harder to be honest about it as traditionally, they are supposed to be the "man of the house" or the ones who bring home the bacon.

They may then resort to charging to credit cards or overdraft facilities to fund their lifestyle to keep with appearances, he adds.

Why it shouldn't be a secret:

It's important to openly discuss monthly household expenses openly, especially if there isn't sufficient money to cover it.

"It's better to work out how to overcome this problem together than to let your spouse wonder who is going to settle the outstanding bills," Raymond says.

Debts

Serene*, a civil servant in her 20s, used to wonder why her husband, Edmund*, a sales executive also in his 20s, could not contribute much to their household expenses.

After much probing, she discovered he owed his credit card company a few thousand dollars. She was angry that he had not shared the truth, as they could have used their savings to clear the debt instead of blowing it all on their wedding.

Why it shouldn't be a secret:

It's best to be honest with your partner to avoid a nasty surprise which could ruin your marriage, advises Yash.

If the debt is severe, you could face legal action. And, if something happens to you, your spouse would have to shoulder the repayment of the debt.

To Tell Or Not To Tell?

There are exceptions to the honesty-is-best policy.

For example, if your spouse is a gambling addict, being honest about how much you have in your bank account or giving him/her access to it, can be disastrous, Raymond says.

Or, if one spouse controls the money too tightly, it will be difficult for the other to be honest about how much he/she earns.

"Couples should have the freedom to spend, as long as they do so within their means after settling their household expenses and putting aside some savings," adds Raymond.

Some financial matters fall into grey areas, like how much allowance to give your parents after marriage.

Unless one partner has to rely on the other's income to make this contribution, this issue may be considered personal. But it can be a minefield if the two of you don't see eye to eye.

"It may be necessary to discuss the issue openly if one spouse's parents require a large sum of money that they are unable to contribute," advises Raymond.

In deciding whether or not to disclose your finances, consider the impact of non-disclosure on your family's financial position and the emotional impact it'll have on the trust between you and your spouse.

Also, determine how critical the information is, says Ai Ling. She suggests these guidelines:

• Must share: An investment, or a job loss or significant pay rise.

• Good to share: An extended family member being diagnosed with a medical condition and possibly needing need financial contribution.

• Probably no need to share: Buying an additional item within your normal shopping budget or receiving a parking summons.

*Names have been changed