你会瞒着另一半去购物吗?

Every couple has secrets. But some secrets are riskier than others, and some come with a price tag.

If one of your secrets is hiding spending, you're not alone.

According to a recent American Express Spending & Saving Tracker of more than 2,000 adults, 27% of respondents have 'misrepresented the amount of a purchase' while 30% said they have hidden purchases from their partner. (I reported on the study in my column for MarketWatch.)

To keep spending under wraps, consumers responding to American Express's survey have gone as far as:

-burying their purchase in the backyard

-pretending that goods came from Goodwill

-hiding purchases in grocery bags to bring them home

-arranging for items to arrive while their partner was away

-sneaking out and bought an item in the middle of the night

'You should not have any secrets from each other regarding money,' Ric Edelman, an author and financial adviser based in Fairfax, Va., recently told me. 'You should be working together as a couple in the management of money.'

But working together when it comes to money can be tough given that many couples want to avoid money topics. In fact, couples say 'they are more likely to know their partner's weight than their salary,' according to American Express.

It's 'very common for people who get married to have no clue as to their partner's income and debts,' Mr. Edelman says. 'This is why money is one of the leading causes of divorce.'

Almost one in three couples say finances cause the most stress in their relationship, and 91% of Americans surveyed find reasons to avoid talking about money with their partner, according to American Express.

The data also indicate that different partners have different thresholds when it comes communicating about spending, with $275 being the average at which 'couples need to consult with their partner before making a purchase,' according to American Express. That level rises to $395 among affluent consumers, and is $249 among young professionals.

Of note, 40% of respondents said they 'believe their partner spends more money than they do on things outside of household expenditures,' while that same percentage 'consider themselves more diligent than their partner when it comes to saving money and budgeting.'

Readers: Are you or your partner a secret shopper? What secret purchases have you made? What is your threshold for letting your partner know about purchases?