More than three quarters of UK mortgage brokers (76%) say the mortgage application process is now faster than it was two years ago, yet complex cases are still failing at key points in the journey, according to new research from Nottingham Building Society.
The findings suggest operational improvements are helping the mainstream process move more quickly, but that progress thins out when a case needs more judgement.
Automated income or credit checks are now the single most common point at which complex income cases fail or stall, cited by 17% of brokers, which points to applications still being tripped up early when income patterns or credit profiles do not fit a standard template.
A further 16% say cases break down at the initial affordability assessment or decision-in-principle stage.
The scale of the issue is compounded when considering the size of what would be perceived as the ‘complex income’ market, with a 2025 UK Finance survey citing that around 28% of mortgage applicants now report income from more than one source. Sage research in 2024 also cited that 47% of the UK population have a second income stream.
Where complex cases still stall
Delays are proving just as damaging further down the line, as 16% of brokers say time delays are causing cases to fall through, while 14% cite evidence and documentation requirements as a key source of friction, reinforcing the sense that even creditworthy borrowers can lose out when a case takes too long or needs more explanation than a straightforward salaried application.
Brokers say those most disadvantaged by current mainstream affordability assessments include people returning from career breaks (32%), borrowers with multiple income streams such as PAYE and freelance work (31%), and applicants with irregular or seasonal income (29%).
Brokers are also clear about where lenders should focus next. A third (33%) say better handling of complex or non-standard cases would have the biggest positive impact on their ability to place business.
Around a third also call for clearer tracking of case progress (33%), better integration between broker systems and lenders (32%) and faster decision making (32%).
Aaron Shinwell, chief lending officer at Nottingham Building Society, said: "These findings show that the market is making progress, but others are still being left behind. Straightforward cases are moving more quickly, which is welcome, yet brokers are still seeing the same pressure points emerge when a borrower’s circumstances need a little more interpretation, whether that is blended income, a career break, variable earnings or a case that simply needs more manual review.
"The next step is targeted improvement at the stages where cases most often come under strain. That means making automated checks more responsive to real-life income patterns, improving transparency as cases move through the system and reducing delays where extra documentation or judgement is needed. If lenders can get those stages right, they will improve outcomes for brokers and for borrowers whose finances may be more complex, but no less credible."
