More than one in ten couples over the age of 40 have never discussed their retirement plans with each other, according to research from Prudential.
The insurer found 11% of couples had avoided the subject altogether, while 19% had not discussed their plans in the last five years.
Only one in ten couples over 40 have seen a financial adviser jointly in the past five years to discuss their retirement.
The research results show that avoiding discussions around retirement led to a mismatch in how much money each half of a couple expects to live on in retirement.
When asked separately to estimate the couple's expected joint retirement income, men said £35,100 on average and women £32,000.
However, it is not just retirement planning that couples avoid discussing. The study found that six per cent have never discussed their finances together and a further 12% have not discussed money for over a year.
Despite sharing a life together, many couples are also reluctant to lay their financial cards on the table at all. About 25% keep their current accounts entirely separate, 30% hold savings in separate accounts and 23% maintain separate investments.
This behaviour could be partly as a result of fears that financial conversations will spark arguments, Prudential said.
Money is the third most likely subject to cause disagreement among couples, with almost a quarter (23%) admitting they fight more about finances than they do about socialising (13%), work (10%), or politics and religion (7%). Family issues (33%) and household chores (27%) top the most likely arguments list.
Vince Smith-Hughes, retirement expert at Prudential, said: "It's easy for couples to put off conversations about finances, particularly longer-term issues like retirement planning, because it's difficult to see any short-term impact. But our research has highlighted some worrying trends.
"Avoiding the conversation is just likely to create a bigger issue in the longer term, so having open, frequent and early conversations about retirement planning really can help couples to remain financially secure."
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