💰 FinTechOn Time📋 Fixed Price

FinTech Mortgage Decision Engine — UK Challenger Lender

UK6 min readUpdated June 2025
Region
UK
Contract
Fixed Price
Tech Stack
8 Technologies
IP
100% transferred

Project Overview

A UK FCA-authorised mortgage lender offering residential mortgages needed to rebuild their mortgage decision e...

Technology Stack

Python/FastAPIPostgreSQLTrueLayer Open BankingExperian APICIFAS APIWeasyPrint (KFI PDF)ReactAWS eu-west-2

Compliance & Standards

FCA MCOB 5/7/11FCA Consumer Duty (PS22/9)UK GDPRPSD2/Open BankingCIFAS membership obligationsCyber Essentials
Step 01

The Challenge

A UK FCA-authorised mortgage lender offering residential mortgages needed to rebuild their mortgage decision engine — a 2012 legacy system that required manual affordability calculations, could not consume Open Banking income verification data, and produced customer communications that failed FCA Consumer Duty Consumer Understanding requirements. The new engine needed to process 400 applications per day with FCA MCOB (Mortgage Conduct of Business) compliance, Open Banking AISP income verification, and automated KFI (Key Facts Illustration) generation. Budget: £140,000.

Step 02

Our Approach

FCA MCOB 11

  • stress-tested affordability calculation (applicant income after income tax and NI, committed expenditure including all other credit commitments, and a stressed mortgage payment at a rate above the product rate as per MCOB 11.6).
  • Open Banking AISP (TrueLayer): 12 months income data directly from employer bank transactions — eliminating payslip fraud.
  • Self-employed: 2-year average from business bank account transactions.

MCOB 5 and MCOB 7

Key Facts Illustration (KFI) must be provided before application proceeds.

KFI generation

  • product selection → total amount payable calculation → APRC (Annual Percentage Rate of Charge) → MCOB-prescribed format KFI as PDF (WeasyPrint).
  • MCOB 7.6: KFI must be personalised to the applicant — no generic illustrations.

Consumer Understanding

  • all customer communications at Flesch reading ease &gt
  • 65.

Consumer Support

complaint pathway clearly signposted at each stage.

Products and Services

APRC clearly disclosed before any commitment.

Price and Value

total cost of borrowing displayed across multiple mortgage terms for comparison.

MCOB declined decision letters

specific reasons, plain English, Financial Ombudsman Service (FOS) referral information.

Experian credit report API

  • affordability credit data, public information (CCJs, bankruptcies, IVAs).
  • CIFAS National Fraud Database screening.

Automated fraud indicator scoring

  • income verification consistency (Open Banking vs stated income), address verification, bank account ownership verification (payee name match).
  • High-risk applications routed to human underwriter.
Step 03

The Results

Engine live at 16 weeks, £132,000 — under budget.

Application processing time: 4.2 days6.8 hours average.

KFI generation: automated — previously 45 minutes manual.

Consumer Duty audit: zero adverse findings — Consumer Understanding outcome scores particularly commended.

Income verification fraud: 3 fraudulent income declarations detected in first month (previously 0 detected — would have resulted in mortgage approvals).

MCOB audit: zero compliance failures in first 6 months.

Client Testimonial
Three fraud cases caught in the first month from income verification. We would have approved all three under the old system. That is £780,000 in potentially fraudulent mortgages that did not complete. The Consumer Duty audit was the cleanest we have had in 6 years." — Chief Risk Officer, UK Challenger Mortgage Lender (name withheld)
ClickMasters Case Study Team
Reviewed by James Whitmore, CTO

Project Details

Sector
FinTech
Country
UK
Status
On Time
Contract
Fixed Price
Tech Stack
8 Technologies
Reading Time
6 min
IP Ownership
100% transferred
Last Updated
June 2025
Written By
ClickMasters Case Study Team
Reviewed By
James Whitmore, CTO

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