Women could be particularly put at risk from not discussing their later life plans - as one in 10 (10%) women expect to fully rely on their partner’s income when they retire, according to the research from Prudential.
The survey of more than 1,000 people aged 40 and over and who live with a spouse or partner found 22% had never talked with them about their financial plans for retirement.
Those who had discussed their retirement finances estimated that they will live on a joint annual retirement income averaging nearly £28,500.
But less than one in three (32%) people surveyed had made arrangements to ensure that if they died their other half would continue to receive an income from their pension.
Around three in five couples (62%) did not know how much annual income they were likely to receive as a couple when they were both retired and 18% did not know how much money their partner has in pension savings.
Some of those surveyed suggested the new pension freedoms had added to the confusion. The freedoms, which can be taken up by people aged over 55, were introduced last year to give savers a wider range of choices over what to do with their pension pot.
Just over one in 10 (11%) people surveyed believe that there are now too many retirement income choices and 38% are worried about making decisions that will lead to them running out of money in retirement.
Some 11% of people are also worried about falling victim to fraudsters stealing their pension money.
The Government-backed Pension Wise service offers guidance to people considering what to do with their pension pot.
Kirsty Anderson, a retirement income expert at Prudential, said: “Life is busy for everyone and it is tempting to avoid difficult conversations, but couples really do need to talk about their finances and retirement planning in particular.
“A conversation about what might happen to a couple’s finances if the worst should happen to one partner can be particularly difficult but it could make the difference between the survivor being left with nothing or having a comfortable retirement.
“Couples who don’t talk about their retirement finances may end up making plans separately and missing out on making the most of the pension saving tax relief available between them.
“They may also have unrealistic expectations of what their combined retirement savings are worth.”