No one is happier to see you married than your mother. But your insurance agent is pretty giddy, too.

Car insurers see stability (and safer driving) in matrimony and reward those who tie the knot with lower premiums. Further discounts come to couples who combine auto policies with renters' or homeowners' coverage with a single company because you are a bigger (and better) customer.

Where else can officially hitched twosomes see savings?

At work: Closely compare benefit plans for duplication. For example, if your spouse can cover your health insurance, maybe you can opt for some of other options such as a cafeteria plan, additional vacation time, supplemental life insurance, or dental coverage for the dog.

At the bank: No matter what banking setup you two kids choose (a single combined account; two separate accounts; his, hers, and ours.) be sure that your bank knows you're legally bound. Accounts that are linked may qualify for lower fees or higher interest rates -- which usually require a minimum deposit across accounts.

In your bills: Sharing dish-washing duty is only part of living under a single roof. Now you get to split the cable bill, the newspaper subscription, and lawn care charges! What about food and clothes? Take advantage of being a bigger consumer by buying the half-gallon rather than the quart of milk, the case of wine, or the really big bag of Doritos. Costco (NASDAQ:COST) was tailor-made for couples.

What to do with all that dough you two lovebirds are saving? How about using it for some friendly competition? Set up mock portfolios, pick stocks, and see who's the better investor.

Oh, and treat your mother-in-law to dinner out once in a while.

More money advice for twosomes:

Fool-for-love Dayana Yochim is the author of The Motley Fool's Guide to Couples & Cash .