Not even our spouse.
According to a recent CreditCards.com report, 7.2 million Americans - 6% - have a bank or credit card account that they keep hidden from their spouse.
And it turns out men are the ones more likely to be hiding money.
Out of the 7.2 million who admitted to keeping a secret account, 4.4 million were men and 2.8 million were women.
The report also found that Americans aren't always 100% honest with their partners when it comes to their spending habits.
One in five Americans have spent $500 or more on a purchase without their spouse knowing about it.
Here again, men are the ones more likely to be dishonest. While only 14% of women have spent $500 or more on a purchase and kept it a secret from their spouse, just over a quarter of men admitted to doing this.
Maybe that's because men are more at ease with being kept in the dark about their spouse's big buys. Almost a third of men said they didn't mind not knowing if their spouse made a purchase of $500 or more. Women, on the other hand, like to know what their spouse spends: Only 18% were okay not knowing about a purchase of $500 or more.
This doesn't mean that Americans think keeping financial secrets is a good idea, though. Just under a third of those surveyed think their partner should let them know when they spend $100 or more.