A third of savers in the UK structure their finances around money which may never enter their bank accounts, National Savings and Investments (NS&I) has warned.
One in three people has based calculations on future income on money they think they will receive in inheritance, borrow, or receive through a pay rise, the study showed.
Characterising Britons as a nation of "financial fantasists", the NS&I survey also showed one in four people stated that they would deal with money difficulties by earning more in future.
Just over one in ten people said they had developed a detailed financial plan for the future, while 55 per cent admitted they hadn't devised a plan at all.
"It is a real concern that such a high percentage of people haven't made a financial plan for the future," commented NS&I's senior savings strategist Dax Harkins.
He added that "there is never any guarantee that people will earn more as they get older".
Instead, consumers should "expect the unexpected" in financial terms and begin saving at the earliest opportunity.
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