Mortgage deals are typically on offer for just 15 days before being pulled, despite homeowners and buyers having the widest choice for 16 years.
This is the shortest shelf-life in six months, according to financial information service Moneyfacts.
As a result, people have little time to decide when rates are volatile.
One adviser said the situation was adding extra stress to a huge financial commitment and making customers feel pressured to make a decision quickly.
“When I recommend a rate – or sometimes a choice of rates – to a client, it’s quite understandable and unsurprising that they want time to consider which one to apply for,” said Jo Jingree, from Mortgage Confidence.
“Some lenders only give a few hours’ notice of a rate change. That creates a situation which is less than ideal because taking out a mortgage can be a huge financial commitment that could impact them for years to come.”
Decision time
The interest rate on a fixed mortgage does not change until the deal expires, usually after two or five years, and a new one is chosen to replace it. Doing nothing would leave people on a variable rate, which is very expensive.
About 1.6 million existing borrowers have relatively cheap fixed-rate deals expiring this year, so need to make their minds up.
Johnny Abbott, from Loughborough, falls into that category and is watching deals with increasing concern.
The 39-year-old and wife Sophie, who have three children, are weighing up whether to get a new mortgage when their current deal comes to an end in July. The alternative is to move to a slightly bigger home that needs renovating, and where the mortgage is only slightly higher.

Everything, Mr Abbott admits, feels like a gamble at the moment. Unless rates start to fall soon, they will have to cut back on costs whichever option they choose. That means no holiday, fewer swimming lessons for the children, no gym or TV subscription.
“We don’t have a massive income, but we feel grateful to be where we are – able to manage costs, and not drowning in them,” the charity debt centre manager said.
“We will just have to do what we can to make things stretch.”
Meanwhile, potential first-time buyers require a new mortgage deal to be secured before they can think about setting up home.
Many are left frustrated by trying to predict the direction of mortgage rates – the interest that is charged on a home loan. Lenders have been switching rates at a rapid pace as the markets try to predict whether or not the Bank of England will cut the benchmark interest rate, the key influence on the cost of many types of borrowing.
Investors expect the Bank’s Monetary Policy Committee to hold rates on Thursday and to make fewer, and later, changes to the base rate of 5.25% this year than previously anticipated. Cuts in this rate, which is at a 16-year high, makes borrowing cheaper.
For those looking for a new mortgage, the current situation is like shopping in a hypermarket, but where everything on the shelf is soon going out of date. Previously, the choice has been more one of a convenience store.
At the start of March, there were 6,000 mortgage products to choose from, according to Moneyfacts, which is the widest selection since 2008.
Lenders have extended their ranges, may offer various extras such as cashback, and – crucially for many first-time buyers – have more products for those who can only offer a relatively small deposit.
The trouble is, the volatility in the market means deals are only around for a few days. The average of 15 days is well down from 28 days at the start of February, and only just above the record low of 12 days last July.
Lenders, aware of what rivals are doing, may pull deals at short notice.
Contact one of our highly experienced mortgage advisors today on 0121 500 6316 to discuss your mortgage needs.