Couples do a lot of things together — including making mistakeswhen it comes to retirement and money, according to NerdWallet — which surveyed 1,800Americans in a relationship (married or living with a partner) tosee how they handled financial decisions.

And what they found was that couples were making a number ofsubstantial mistakes when approaching saving for retirement. Amongthose errors:

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  • Failing to take action.

  • Not talking to one another about what they were (or weren’t)doing.

  • Making basic mistakes on how to take advantage of variousretirement savings strategies.

  • Having no idea of what their savings targets should be.

Some of these are simple communication issues, since it’s noteasy for people to talk about money — sometimes especially withthose closest to them.

But other mistakes go deeper — and sometimes both partners knowabout it, but just don’t take steps to change behaviors that canendanger a couple’s retirement. Other times, one partner’signorance of what the other is doing — or not doing — can be theproblem.

Regardless of how deep the problem is and what causes it, someof those mistakes can endanger a couple’s retirement, since theycan derail savings and leave them without enough money to live ononce they’ve departed the workplace. Or those mistakes could meanthat one, or both, halves of a couple won’t be retiring at all.

Here’s a look at eight mistakes the survey found couples makingwhen it comes to preparing for retirement:

How much will we need for retirement? Couples need to focuson this question. (Photo: Getty)

8. They don’t deal in specifics

While 76 percent of Americans in a relationship in which atleast one partner is saving for retirement say they’ve discussedgeneral retirement planning, such as the age at which they mightlike to retire, where they might want to live and what they want todo, they don’t get into the nuts-and-bolts issues—like how muchmoney they’ll need.

In fact, 30 percent of respondents in a relationship who said atleast one partner was saving for retirement said they haven’tdiscussed how much they should be saving to get them through theirretired years.

Related: It's time to help clients double-check theirsavings discipline

Fewer than half of workers or their spouses have tried tofigure out their retirement needs. (Photo: Getty)

7. They just don’t want to know

According to the Employee Benefit Research Institute, fewer thanhalf of workers or their spouses have attempted to figure out theirretirement needs. Why not? Fear.

The NerdWallet report quoted Jack VanDerhei, EBRI researchdirector, saying, “People are too scared to see the results, orthey think they are too old to do anything to improve their overallretirement adequacy.” He continued, “But no matter how bad the newsis, you’ll be a lot better off if you start dealing with ittoday.”

Related: Nearing retirement? Get prepared

Many partners don't know their spouse's contribution ratethey're saving for retirement. (Photo: Getty)

6. They keep it a big secret

People in a relationship aren’t necessarily letting theirpartners know how much they’re saving toward retirement, with 21percent who are putting money away saying that their partners don’tknow their contribution rate.

Related: Women, minorities and millennials face ownchallenges in retirement saving

Few respondents in the survey said they had a brokerageaccount. (Photo: Getty)

5. They don’t have brokerage accounts

Even if they’re not the best choice for retirement savings,brokerage accounts can offer a way for couples who aren’t eligiblefor IRAs or aren’t offered 401(k)s at work to set aside money thatmight grow at a faster rate than in a bank savings account.

But only 14 percent of respondents who are married or livingwith a partner say they have such an account, and only 4 percent ofthem say their partner does.

Related: Leadersboards, dire headlines, and encouragingretirement saving

Discussions about possible trading decisions aren'thappening with many couples. (Photo: Getty)

4. One partner trades stocks without telling the other

Of the 14 percent of respondents in a relationship who said theyhad brokerage accounts, 43 percent don’t discuss possible tradingdecisions in their account with their partner before takingaction.

So one partner could get the couple into serious financialtrouble without the other partner even having a suspicion thattheir retirement funds could be toast.

Related: 10 places where retirement security is better thanin the U.S.

Using a savings account for retirement savings is all wrong,but still couples do it. (Photo: Getty)

3. They’re doing it wrong

While 43 percent of respondents in a relationship say their mainretirement savings vehicle is a 401(k) plan, 31 percent are using asavings account instead, despite pitifully low interest rates—thusforgoing the tax breaks and other potential advantages of a 401(k)to grow their savings.

The same holds true for IRAs; just 25 percent are using an IRA,compared to that 31 percent using savings accounts.

Related: Roth IRAs may work for older savers afterall

How much is in their partner's retirement account? Manyspouses don't know. (Photo: Getty)

2. They just don’t know

Among the 36 percent of Americans in a relationship who say thattheir partner is saving for retirement, 23 percent say they have noidea how much their partner contributes to long-term retirementaccounts.

And 21 percent say they don’t have any idea how much money is intheir partner’s retirement account.

Related: 10 best big cities for retirement

A scarily substantial portion of the repondents surveyedsaid they're not saving for retirement. (Photo: Getty)

1. They’re just not saving for retirement

One out of three respondents in a relationship — 33 percent —said that neither they nor their partner are saving for retirementat all.

Related: The Labor Day guide to putting your money towork