Three quarters of mortgage holders do not know how an increase in interest rates of one percentage point would affect their budget.
Some do not know what type of mortgage they have or even when it expires, a poll has found.
The survey of 2,262 people was conducted for an education group, the Consumer Financial Education Body.
The Bank rate has been kept at 0.5% for 15 months in a row, with the latest decision last Thursday.
Poll
Key findings of the survey included:
* Some 51% of those asked believe interest rates will change in the next nine months
* One in seven (15%) do not know whether they are paying a fixed, standard variable, tracker or discounted rate
* Some 8.6 million people, out of 14.6 million people in the UK who have a mortgage, have a time-limited deal
* One in seven (15%) of these people do not know when their deal expires
To assist them, the group has updated its mortgage guides on the Moneymadeclear website.
Tips include checking “key facts” paperwork provided by a lender when the mortgage was taken out. This shows when the deal comes to an end.
