The number of cases where at least one lender was available to meet the loan needs of self-employed mortgage applicants plunged from 71% in January to 67% in February as lenders tightened their criteria for these customers, the index revealed.

Indeed, last month, 31% of cases were considered to be unaffordable based on the clients required loan amount.

In contrast, across the whole of the market, 79% of cases were affordable in February, which is slightly down from the peak of 80% in January. There was at least one lender able to meet the loan requirements of 86% of first-time buyers, 84% of remortgage customers and 81% of home movers.

MBT said the average maximum loan available to self-employed mortgage applicants dropped by just over 2% to £216,000 in February.

However, the biggest change was the average minimum loan available, which fell by more than 18% to £96,935 – reflecting a significant tightening of self-employed affordability criteria amongst some lenders.

Tanya Toumadj, CEO at Mortgage Broker Tools, said: “The self-employed continue to face a complex affordability landscape as more lenders tighten criteria for mortgage applicants in this group and the number of options reduces.

“We have also seen the spread between the average minimum available loan size and the average maximum available loan size widen to more than £119,000.

“For brokers who only try one or two lenders, this can give a false impression that their clients have no chance of achieving the loan size they require.

“However, it’s important to remember that there was at least one affordable option for more than two thirds of self-employed cases processed through the MBT Affordability platform in February.

“The message here is that the choice of lender makes a big difference to the amount a self-employed mortgage applicant can borrow, so brokers need to make sure they are considering all of the affordability options to ensure they are providing their clients with the most suitable recommendations.”