The Single Most Important Money Talk for Couples

Married for 38 years, San Jose couple Carol and Ron Beck started getting serious about retirement in their mid-thirties. By that time, they had two kids and realized they needed to be thinking about their family's future. So they set some savings goals, and continued talking about their plans in the years and decades that followed. Ron planned to retire around 65, and did. Carol is expecting to quit in the next two years. "We're still deciding where we'd like to retire to," Ron says. But even on that they have a good idea: a home near their daughter in Monterey, Calif.

There's no question that couples need to plan together for retirement. In fact, since amassing the requisite amount of money will take time, retirement should typically be first on the list of priorities. "When it comes to goals, everything else comes next," says Elizabeth Grahsl, a financial planner in Dallas.

A new Money poll of boomer and millennial couples suggests that we may need a little more help with this goal then we think. Some 79% of millennials and 91% of boomers surveyed say they are in agreement with their partners on saving for retirement. But Money also found that, among people who are married or living with a significant other, one in 10 boomers and four in 10 millennials don't know their partner's retirement account balance, while 14% of boomers and 40% of millennials don't know when their partner plans to retire. That backs up a 2013 Fidelity poll that found that 38% of couples disagree on the lifestyle they expect, 36% on where they will live, and 32% on whether they will work. The costs of not being aligned are substantial: You could end up with less than you need at the finish line.

Here's how you can avoid such a fate while strengthening your union and your finances.

Know your retirement wish lists. Since the amount of savings you need depends on your wants, create a "vision plan" together, says Brad Klontz, a financial psychologist and the author of Mind Over Money. Both of you should write down at what age you want to retire, where you want to live, and what you expect your life to look like. Do you want to stay put, downsize … sail around the world? "Come to the table with your dreams," Klontz says. "Where you agree, it will be easy to adjust your finances because you are excited."

Do a reality check. First, are you saving enough for the life you want? Check what your nest egg is on track to produce in annual income with T. Rowe Price's Retirement Income Calculator, and see if that squares with your vision.

Second, keep in mind that retiring at the same time as your spouse typically isn't the best move. Wives are often younger than their husbands, and women have longer life spans, so if a wife retires with her hubby, she'll probably need to draw from their retirement savings for longer.

Also figuring into the equation are Social Security benefits, which make up 38% of income for the average retiree and which you'll also want to coordinate with your spouse. One way to maximize benefits is to "file and suspend." The higher earner files, then immediately defers benefits to let them grow (they rise 8% for every year you delay between full retirement age and 70). Assuming the lower earner is at full retirement age, he or she can then claim a spousal benefit, deferring his or her own benefit, which will also rise in the meantime. As you near retirement, run this and other basic scenarios using the benefits planner at ssa.gov or more detailed ones at maximizemysocialsecurity.com ($40).

Create a holistic plan. Make sure you're acting as a team when it comes to saving and investing. If you're a two-income household, you probably have access to two 401(k)s, for total annual tax-deferred savings of $36,000, or $48,000 if you're both 50-plus. Stash at least enough in each to get the full company matches. If you can't max out, sign up for automatic increases as your pay rises. "This is so basic it's like breathing," says O'Kurley, "yet a lot of couples don't talk about it."

You also want to think of your portfolio as one, and make sure you don't have overlap or overexposure in your overall mix. The Instant X-Ray tool at Morningstar.com can help you figure this out. As a general rule, the percentage of your portfolio in stocks should be equal to 110 minus your age; the rest should be primarily in bonds. But if one or both of you have a traditional pension, you could adjust the bond allocation lower, since the guaranteed income allows you to take more risk.

Got several years between you or different tastes for risk? A UBS survey found that half of couples have divergent risk tolerances, but among them, those who choose an allocation between their preferences tended to be most satisfied. It's also okay for the more risk-averse partner's plan to be tilted toward bonds and the other's to serve as a counterbalance in stocks, if that keeps the nervous one from overreacting to volatility. Another reason to split the baby: If your plan has lousy bond fund options, say, you could use your spouse's plan to fulfill that allocation while using your 401(k) for stocks.

More from Love & Money:
Poll: How Boomer and Millennial Couples Feel About Love and Money
Why Couples Need to Get Financially Naked
This Is the Magic Number That Can Help Couples Avoid Money Fights