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Model 4.1 — Validated against 2,070 cases

Understanding
Underwriting Complexity

Data-driven insights into what makes mortgage cases hard —
and why it matters more every quarter.

12+
Scoring Factors
24mo
Analysis Window
4
Complexity Tiers
01 / 08
The Problem

Complexity is rising.
This isn't perception — it's measurable.

Over two years, the average complexity of cases entering underwriting has increased significantly. But the impact on operations has grown even faster.

+7%
Average complexity score
47 → 51 points
2×
Days to underwrite
More than doubled
4×
Document requests per case
Quadrupled in 24 months

Population: completed cases entering underwriting (offer, conveyancing, withdrawn, rejected, completed) over the last 24 months.

02 / 08
The Model

12 factors. 1–10 scale. 4 tiers.

Model 4.1 scores every mortgage application by combining income complexity with case-level risk factors.

+20 Loan size > £750k
+20 Non-standard repayment type
+15 Foreign national
+15 Lending into retirement
+15 Policy / funder exceptions
+15 Debt consolidation
+15 High LTV > 90%
+10-15 Tight affordability buffer
+10 Purchase / remortgage + capital
+10 Physical valuation
+5 Down-valuation (physical)
+5 SIRA fraud check not clear
Low <3.5
Medium
High
Very High 6.5+
1.0 3.5 5.0 6.5 10.0
03 / 08
Validation

The model predicts real effort.

Very High tier cases consistently take 2–3× longer to underwrite than Low tier cases. The score maps directly to operational cost.

Average Days to Underwrite by Tier
Quarterly average, completed cases
Low Medium High Very High
2.1d
3.5d
5.0d
6.8d
Q1 2024
2.3d
4.0d
5.5d
7.5d
Q3 2024
2.7d
4.4d
6.0d
8.0d
Q1 2025
2.9d
4.8d
6.5d
8.3d
Q3 2025
Very High tier: 2–3× longer than Low tier, consistently across quarters
04 / 08
Root Cause

One factor dominates the shift.

Foreign national cases surged from 13% to 34% of the book. Income mix stayed flat — it's case-level factors driving complexity up.

+21pp
Foreign Nationals
13% → 34% of underwriting cases. The single biggest driver of increased complexity.
+8pp
Tight Affordability
More cases with disposable income buffer ≤ 5%. Tighter margins = more scrutiny.
+7pp
SIRA Not Clear
Fraud check flags requiring manual review. Growing alongside foreign national volume.
−13pp
Physical Valuations
Shift to AVM/desktop valuations partially offsets rising complexity elsewhere.
∼0pp
Income Mix
Self-employed, contract, and multi-source income ratios have stayed flat. Not the cause.
05 / 08
Portfolio Mix

The book is shifting toward harder cases.

Low-complexity cases dropped 11 percentage points. High and Very High tiers are growing — meaning more resource-intensive work as a proportion of volume.

Q1 2024
42% Low
30% Medium
18% High
10% Very High
−11pp
~0pp
+6pp
+5pp
Q1 2026
31% Low
30% Medium
24% High
15% Very High
39% of cases are now High or Very High, up from 28%
06 / 08
Implications

What this unlocks for the business.

01
Predict workload before cases arrive. Every application gets a complexity score at DIP — we know the effort before underwriting begins.
02
Tier-driven resource planning. Staff allocation and SLAs can be differentiated by complexity tier, not just volume.
03
Factor complexity into product decisions. Distribution and pricing can account for the true operational cost of case complexity.
04
The foreign national segment is the key lever. At 34% of the book and rising, understanding this cohort is critical for operations, product, and risk.
05
Data-driven operational planning. Complexity scoring replaces gut feel with quantifiable, trackable, forecastable metrics.
07 / 08
Gen H Data & Analytics

Data-Driven Underwriting
at Scale

Gen H is one of the few lenders that can quantify the true cost of complexity in its book. This capability enables smarter resource allocation, better SLAs, and more informed product decisions.

Smarter Allocation
Tier-driven staffing
Better SLAs
Complexity-adjusted targets
Informed Products
Priced for complexity
08 / 08