Paul Miles — IRB Requirements and CLM Implications (DRAFT v0.1)

Tag: S-2026-04-29-paul-irb-clm-briefing Type: own-writing Author(s): Paul Miles (Red Strata) Date of source: 2026-04-23 (document date); 2026-04-29 (Open Brain capture) Date ingested: 2026-05-17 Authority weight: own-writing. Raw file: Open Brain corpus snapshot at /_raw_sources/open-brain-2026-05-17-corpus.md. Document on disk: ~/AgentData/ClaudeAccess/Projects/03 Credit Lifecycle/Regulatory/2026-04-23 IRB Requirements and CLM Implications v0.1 DRAFT.docx (32 pages, A4, DRAFT v0.1).

What it claims

Client-facing briefing translating Internal Ratings-Based (IRB) approach requirements into design implications for both Day 1 (legacy-architecture simplification into a consolidated golden-source target) and Day 2 (the CLM build) at an Irish Tier-1 retail bank.

Structure. Cover; document control; TOC; executive summary; §1 IRB landscape (CRR / CRR2 / CRR3, EBA IRB Repair Roadmap, ECB SSM, CBI); §2 definition of default and IRB data lifecycle (CRR Article 178, materiality threshold under CDR 2018/171, EBA/GL/2016/07, EBA/GL/2017/16 PD/LGD, EBA/GL/2020/05 CRM, validation, use test, Article 143 model change, Articles 148–150 roll-out and partial use, Pillar 3 CR6/CR7/CR8/CR9/CR10, COREP/FINREP, BCBS 239 / RDARR); §3 Day 1 implications; §4 Day 2 implications; §5 cross-cutting requirements; §6 eight named recommendations; §7 eight open questions; Appendix A regulatory reference list; Appendix B glossary (29 IRB terms); Appendix C mapping table (14 IRB data inputs → system-layer path → DQ control/metric/target → owning role).

Anchored to. CRR3 (Regulation (EU) 2024/1623, in force 9 July 2024, applies 1 January 2025, 72.5% output floor phased to 2030); EBA Roadmap and Guidelines; ECB Guide to internal models (February 2024); ECB RDARR Guide (May 2024); BCBS 239 (January 2013); CBI Regulatory & Supervisory Outlook 2025–2026; CBI CP123 on materiality threshold.

Headline Day 1 implications. Every IRB rating-model input must end up with a single governed golden source after simplification, with lineage continuity, default-history continuity, retention preserved (5 years), and a model-change impact assessment per CRR Article 143.

Headline Day 2 implications. Canonical Definition of Default (DoD) logic in the CLM ODS; UTP flag set as structured capture; full IRB lineage as a named subset of the CDE register’s 100% R1 lineage target; CLM ODS as certified single source for Pillar 3 IRB templates and COREP IRB datasets; use-test evidence engineered into the CLM UI audit trail.

Eight recommendations. Add an IRB design lens to the CLM Design Sub-Committee; tag IRB-relevant CDEs in the existing register; implement canonical DoD logic in the CLM ODS; treat the CLM ODS as the certified Pillar 3 / COREP source; extend the BCBS 239 attestation to include named IRB capabilities; engineer use-test evidence into the CLM UI; govern Day 1 simplification through model-change impact assessments; engage the JST early.

Status. DRAFT v0.1 with 8 open client-confirmation items (SI vs LSI status, current IRB scope, materiality threshold parameters, model-owner mapping, use-test evidence retention policy, Pillar 3 cadence and template-population responsibility, JST engagement protocol, historical default-flag back-fill scope). Two intentional [TBC with client] markers remain in Document Control.

Notable quotes

None — own-writing.

What’s speculative vs. asserted

• Asserted: regulatory references, structure, anchors, the 8 recommendations.
• Speculative / contingent: the 8 open questions remain unresolved pending client confirmation; the briefing is DRAFT v0.1.

Topics this feeds

• IRB Requirements and CLM Implications Briefing
• CLM Transformation Programme
• BCBS 239 and Data Lineage

Open questions raised

All 8 client-side open items above (see open-questions for the consolidated list).

Ingestion note

Single Open Brain task-type thought dated 29 April 2026. The captured detail is unusually full — most of the page content is direct from that single thought.