Your partner rushes to get the mail first. "They insist on collecting the mail and sorting through it before you get the chance," Detweiler said. Or they get a separate mailbox account but don't let you have a key.
Something just doesn't add up. Plenty of families have trouble getting their paychecks to stretch through the month. But if you make decent money, have reasonable expenses and still come up short, hidden debt may be the reason why. "If you think you should have more left over at the end of the month and you don't," Rhode said, "money may be vanishing to fuel your partner's spending or debt."
Creditors are calling. Who could ignore this red flag, right? But your partner may explain it as a case of mistaken identity or a misunderstanding that will be soon cleared up. Maybe, or maybe you're about to get sued.
Your liability for your spouse's secret debt varies by the type of debt, how it was acquired and your state. In community-property states -- Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington and Wisconsin -- debt incurred during marriage is typically considered joint debt, even if it's in just one person's name. In other states, debts in one person's name are typically separate.
But there are exceptions in both types of states. Divorce expert Ginita Wall of San Diego had a California client whose husband had incurred tens of thousands of dollars in credit card debt by bailing prostitutes out of jail. Since his little hobby didn't benefit the "community" of their marriage -- quite the opposite -- the divorce court ruled it was his debt alone.
In states that don't have community-property laws, debts of one spouse still can become the other's responsibility, if the money was spent for "family necessities" such as food, clothing or shelter, or was used to maintain jointly owned assets. Books like Nolo Press' "Divorce & Money" by attorney and financial planner Violet Woodhouse can help you figure out your liability. Or you can talk with a divorce or bankruptcy attorney about your state's laws regarding debt.
If you're still in the dark about whether your spouse is hiding debt, or how much, here are some ways you can uncover the truth:
Review your credit reports together. Most debts will show up here, with the exceptions of retirement-plan loans, loans to family members and illegal debts, such as money owed to criminal loan sharks.
A spouse who balks at sharing credit reports is "a good, clear signal that we're not sharing things the way that we should be," said Wall, a CPA and certified financial planner who co-founded WIFE.org, a financial-education site for women.
Even if your partner won't cooperate, you can at least look at your own credit reports to see if there are accounts you don't recognize. One woman's husband forged her name on seven credit cards and a second mortgage before she caught on.
Check your paperwork. If your spouse took out a secret retirement-plan loan, the payments would show up as deductions on his or her pay stubs. You should scan bank and credit card statements as well. Mysterious deductions or big cash advances from these accounts are signs something's wrong.
If all else fails, do a "midnight audit." What if your mate is secretive about paperwork or won't give you access to your accounts? It may be time to do what Wall calls a "midnight audit," which means snooping around when your spouse is asleep or out of town. She advises making copies of any financial paper that seems relevant.
Even if you don't understand what a financial document is all about, you can take it to a financially savvy friend or an attorney for decoding.
All this assumes that your partner isn't violent and that you aren't worried about getting physically hurt if your activities are discovered. If you are worried about that, you should contact your community's battered-spouse hotline for advice.
Otherwise, keep in mind that it's relatively hard to keep debt hidden from a determined searcher.
"Things show up," Wall said, "when you open your eyes and look."
Liz Weston is the Web's most-read personal-finance writer. She is the author of several books, most recently "The 10 Commandments of Money: Survive and Thrive in the New Economy" (find it on Bing). Weston's award-winning columns appear every Monday and Thursday, exclusively on MSN Money. Join the conversation and send in your financial questions on Liz Weston's Facebook fan page.
