Saving for retirement is no easy task and it can be particularly challenging for couples. When there’s a lack of communication about money matters or you’re not in agreement on how your savings should be invested, that can throw your entire retirement planning strategy off course.

Fidelity Investments’ 2015 Couples Retirement Study sheds some light on how problematic retirement planning can be when it’s a team effort. According to the survey, 47 percent of couples disagree about how much money they’ll need to maintain their lifestyle in their later years.

A NerdWallet survey conducted by Harris Poll found that 33 percent of couples said they weren’t saving anything for retirement. Among those who are saving, 1 in 5 respondents said they were clueless about how much their significant other was contributing to their retirement accounts.

So how can couples ensure that they reach their retirement goals? Knowing which mistakes have the potential to be the costliest is a good place to begin.

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Investing without a plan can doom your retirement. That’s the message David Walters, a certified financial planner with Palisades Hudson Group in Portland, Oregon has for couples.

“Retirees or soon-to-be retirees that haven’t planned ahead are destined for failure,” Walters says. “Not understanding where you need to be financially makes it all the more likely that you won’t achieve your objective.”

Hagen Pruemm, a retirement income certified professional and president of SIS Financial Group in Hoffman Estates, Illinois, points out that in addition to planning to save, couples also need a plan for how they’ll spend their retirement income.

“I see people who have their retirement savings all over the place in several different accounts, with no overall plan for retirement income,” Pruemm says. “They don’t really know what account they should draw from, and how much they’ll be able to draw in order to have enough income for the rest of their lives.”

Taking a closer look at how much you’re saving, where you’re putting your investments and what withdrawal rules apply, if any, can help you formulate a plan for tapping your assets when the time comes.

Overlooking differences in your investing styles can also lead to trouble. When it comes to investing, men and women are often divided in their approach. Steve Lewit, CEO and co-founder of Wealth Financial Group in Buffalo Grove, Illinois, likens the gap to the Grand Canyon.

“Most men and women approach investing and money from very different perspectives,” Lewit says. “Men tend to be more aggressive and want to win, especially in the short term. Women typically take a more conservative, long-term view.”

Annalee Leonard, founder and president of Mainstay Financial Group in Pensacola, Florida, says that age also influences investing outlooks.

“Women are often more conservative investors at a younger age,” Leonard says. Men, on the other hand, may not begin to adopt a more conservative mindset until they reach middle age.

When couples can’t agree on how to allocate their assets, that can wreak havoc with their portfolio. Without compromise, you may end up exposing yourselves to too much risk or playing it too safe and missing out on higher returns.

The solution to avoiding conflicts over how to invest is simple, according to Leonard.

“Talk to each other. Have goals. Be prepared to compromise for your spouse,” she says.

Don’t skip out on the details. Terry J. Siman, managing director with United Capital in Philadelphia, says that it’s sometimes the smaller things that trip couples up as they plan for retirement.

For example, he points out that couples often fail to consider what the transition from earning a salary to living off passive income involves. Taxes can be a stumbling block if couples aren’t accounting for an increase in their tax liability as they begin withdrawing assets from qualified retirement accounts.

Not having a clear idea of what their retirement lifestyle will cost is another common oversight that can have significant financial repercussions.

“Many families want to actually spend more in the early years of retirement,” Siman says.

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If you and your partner want to splurge on things like travel or entertainment once you retire, you need to be looking at your budget through a highly focused lens. While you may be spending less on transportation if you’re not commuting to work every day, other costs, such as health care, could increase.

Getting into the nitty-gritty details of what you anticipate spending in retirement can give you an idea of whether your plan is sustainable.

Planning needs to cover both spouses, not just the breadwinner. One pitfall Leonard advises couples to watch out for is the ‘it’s my money because I worked for it’ syndrome.

She encourages couples to work together, with both sides having a say in how their money is spent or invested, regardless of which partner is the wage earner.

Michelle Herd, a certified financial planner and senior client advisor at TFC Financial Management in Boston, says that assets should be owned and accumulated as evenly as possible between spouses, independently of who earns the income.

“An uneven divide in the ownership of assets can trigger unforeseen consequences with cash flow, estate planning and taxes later in life,” Herd says.

She recommends utilizing a spousal IRA as a retirement planning tool so the non-working spouse can accumulate some assets. Herd also urges couples to make sure they have adequate health, disability and life insurance coverage for both spouses.

Retirement planning doesn’t stop at investing. Investing wisely is certainly important but for Pruemm, being prepared for every eventuality is a critical part of a complete retirement plan.

“If you plan on retiring early, make sure you budget and plan for bridging the years before Medicare kicks in,” Pruemm says, since being without health care coverage could be financially devastating.

He says couples should be looking at whether the need for long-term care could become a possibility. Putting safeguards in place ahead of the death of one spouse is also important so that the surviving spouse isn’t overwhelmed with financial stress in addition to the emotional stress that accompanies such an event.

If you’re struggling to get a grip on what scenarios you and your spouse need to be planning for, enlisting the aid of a professional may be the logical step.

[See: 13 Ways to Take the Emotions Out of Investing.]

“Talk to a specialist,” Pruemm says. “Don’t try to figure it out yourself. Retirement planning is very complex and help from an expert can get you on the right track.

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5 Common Investment Mistakes That Couples Make originally appeared on usnews.com