Togetherness has its perks in the financial world -- price breaks on insurance premiums, saving money by splitting bills, instant justification for buying the family-sized bag of Doritos, and so on.

However, when it comes to credit, too much togetherness can be bad for your bottom line. Even though there's no such thing as a "couples" or "joint" credit report, if you both are named on a loan or listed as joint account holders, any flub-up (late payments, defaults) on the account will mar both of your credit files, no matter who forgot to put the mortgage check in the mail.

Couples need to be a little selfish to keep their credit healthy. Should the unthinkable "d" words come up (namely, "divorce" or "death"), you want to be able to stand on your own two feet, creditwise. You don't want a Mr. or Ms. Wrong or, worse, an untimely demise mangling your credit.

A few simple moves now will keep things harmonious on the home front -- and in your credit files.

1. Don't lose your autonomy: It might be tempting to put all your cards in each of your names, but doing so robs you of your stand-alone reputation. Keep the accounts you established in your single days open. In fact, don't even relegate those cards to your sock drawer -- use them for a small purchase at least every few months to keep them active. When you stop using your cards, your credit file can quickly go dormant. As little as six months of no activity on an account can make you unscorable. (You'll still have a credit file, but without anything for your lenders to report, the credit-scoring system just kind of gives up.)

What's the big deal? If you find yourself on your own because of either of the aforementioned "d" words, your access to lines of credit could be swiftly cut off. Without established and active credit in your own name, you'll have a harder time qualifying for loans or new cards.

2. Share your credit secrets: Put it all out on the table. Pull your free reports at annualcreditreport.com, dim the lights, and review each others' reports (without judgment or eye-rolling!).

3. Make your sweetheart an "authorized user": That designation is a lot easier to undo than "joint account holder" on cards you want to share. Again, apologies for being a downer, but if things go south in your relationship, untying the credit knot can be as complicated as figuring out who has to take the bread machine if you're both unwilling to let go of joint accounts.

4. Vow to pay those bills on time: Nagging's not attractive, but a few moments of bickering about whether or not payments were sent in on time is better than months of trying to clean up a credit mess.

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This article was originally published as 4 Credit Rules for Coupleson Fool.com

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