When it comes to money, how much do you really know about your spouse? Though husbands and wives almost always share a bank account (and secrets, and, well, everything else), the findings of a new survey conducted by Fidelity found that a shocking 43 percent of spouses don't know how much money their partner makes.

It wasn't a mere fill-in-the-blank question for the married men and women who participated. The study concluded that four in 10 married people surveyed couldn't correctly identify which salary range their spouse falls into, and that about 10 percent of those who got it wrong were off by more than $25,000.

"We know couples don't always agree when it comes to money, but we were surprised how many missed the mark on the question of their partner's salary," John Sweeney, executive vice president of retirement and investing strategies at Fidelity, told Fox Business of the findings.

There were some other interesting conclusions along with the big-picture statistic. For starters, there was no gender gap -- 43 percent of both men and women were incorrect about their spouse's salary. Additionally, the rate of wrong responses went up 16 percent from when the same survey was conducted two years ago.

The reason for the lack of communication comes down to societal expectations; a too-high or -low pay grade comes along with a set of preconceived notions. "Talking about money is the last remaining taboo and is far more 'off-limits' a topic than even sex," Dr. Daniel Crosby, a behavioral finance expert and president of IncBlot Behavioral Finance, told Fox Business.