Its analysis shows up to 19 lenders - around one in five of all lenders - currently charge non-refundable booking fees on some of their mortgage products ranging from £100 to as much as £999.
Lenders are increasingly imposing non-refundable fees to cover their costs in processing applications and booking preferential rates - and if borrowers go through to complete the application they are not affected.
But with more borrowers at risk of failing to complete applications the company warns that customers could lose out. People who pull out of a deal will almost certainly have to pay the fee although some lenders say they will not impose the fee if an application is declined.
Lenders who impose the fees on some of their products include HSBC which has the highest fee at £999, Abbey with £995, Nationwide, Yorkshire Building Society, Standard Life Bank and Hinckley and Rugby Building Society.
Julie Speed, national accounts director at Evaluate Technologies said: “The picture on fees is becoming more and more confused and the issue of non-refundable fees is not helping.
“Lenders will argue that they face costs in processing applications and if they reserve a product for a customer and that is fine as far as it goes.
“But if customers are turned down for a mortgage or are forced to pull out of a deal it will be an extremely unpleasant surprise to find that not getting the mortgage you wanted is going to cost you a lot of money. Clearly customers need to be certain that they want a mortgage when they start this process, otherwise they could end up incurring unnecessary costs.”
Lenders who include non-refundable booking fees in their terms and conditions also include Cheltenham & Gloucester, Britannia, Ipswich Building Society, Leek Building Society, Stroud & Swindon, Marsden, Nottingham and Skipton.
The average fee charged is around £405 with the lowest coming from Nationwide and Cheltenham & Gloucester at £99 and Leek Building Society at £100.
