Nationwide has warned that many are "chronically underprepared" for additional costs, with 21% saying they can only just afford to get by.
The average household spends 24% of income on mortgage or housing costs, but one in ten (11%) spend 50%.
After paying for housing and bills, one in five (22%) are left with less than £100 of disposable income each month.
9% said they would need to cut spending elsewhere in order to make ends meet.
The researsh also shows that attitudes ary sharply between those who voted to Remain during last years’ referendum, and those who voted to Leave.
Twice as many ‘Remain’ voters have reduced spending than their ‘Leave’ counterparts (16% vs 8%).
Almost half (44%) of Brits agree there will be financial consequences as a result of Brexit, anticipating increases on the price of food (56%), holidays (49%), utilities (42%) and fuel (38%).
One in ten (11%) are already cutting back and 10% are saving in anticipation of a Brexit impact.
Others are putting off borrowing money (6%), buying a home (5%), a new car (5%), or even moving jobs (5%) as a direct result of Brexit concerns.
Dan Wass, Nationwide’s Director of Banking and Insurance, commented: “We’re facing uncertain economic times, so it’s interesting to see what consumers make of it all and how this is already influencing their thinking about day-to-day finances. While we don’t know what the effects of Brexit will be or indeed when the Bank base rate will rise, now is the time to take action - ensuring you have the best products and services to meet your needs.”
