The software company queried 1,046 married adults, with 7 in 10 couples saying they agree on a holiday spending limit. But of those, 47 percent say they have deceived their spouse about how much they spent on gifts.

Another survey , from Quicken, came to a similar — but somewhat more ominous — conclusion.

Almost half of Americans say their spouses or significant others do not know how much they spend during the holiday season, according to a new survey of 1,000 U.S. adults from Swagbucks.com.

For many consumers, the real magic of the holiday season is the sleight of hand it takes to hide overspending from their spouse.

Some of the problem could stem from a mismatch in ideas over who's in charge of the holiday shopping. In the SwagBucks.com survey, 85 percent of women said they do all of the shopping, while 46 percent of men said they do.

The ease of online shopping — which often does not even require taking your credit card out of your wallet these days — also makes it easier to lose track of your own spending, as well as your partner's, said certified financial planner Lili Vasileff, founder of Divorce and Money Matters in Greenwich, Connecticut.

But couples who keep each other in the dark about holiday spending (purposely or not) are setting themselves up for trouble. In a survey earlier this year of 2,145 adults from the National Endowment for Financial Education, 75 percent said financial deception has had a negative effect on their relationship.

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"If people are communicating about [the spending], then you wouldn't have issues," Vasileff said. "I think what gives rise to conflicts is the lack of the communication, which is the number one source of conflict in marriage."

Holiday overspending can have financial consequences, too, including debt, said Tiffany Welka, vice president of VFG Associates in Livonia, Michigan. To stay on track, work together to set out a budget or spending plan. Stick to charging only what you can pay off in full each month.

"Spending more than that leads to trouble," she said.