The Prudent Underwriting Matrix
1. The problem with "prudent"
Article 124K(2)(a) requires that an ADC exposure be "subject to prudent underwriting standards, including for the valuation of any real estate used as security for the exposure." This is the gateway condition. Without it, neither pre-sales nor borrower equity matter. The lender cannot access 100%.
But what does "prudent underwriting standards" mean? The rulebook provides exactly one definition:
An institution shall have an underwriting policy for originating real estate exposures which shall, at a minimum, require the institution to assess the ability of the borrower to repay. PRA2026/1, Article 124B(1)
That is the complete definition. "Assess the ability of the borrower to repay." There is no list of required checks, no prescribed metrics, no minimum documentation. The PRA expects each lender to form their own view and be able to defend it.
This is not an oversight. It is how the PRA operates. They set principles, not checklists. The question a supervisor will ask is not "did you follow the checklist?" It is "can you demonstrate that your underwriting remains prudent across the life of this facility?"
This paper maps every PRA requirement relevant to ADC classification and answers three questions for each:
- How specific is the PRA? Does the rulebook give exact thresholds, or is it left to the lender?
- What evidence is needed? What would a lender need to show a supervisor?
- What does Mintstone cover? What is built, what requires lender input, and what is outside scope?
2. How to read this matrix
Each requirement is tagged with one of three specificity levels:
| Tag | Meaning | Example |
|---|---|---|
| Prescribed | The PRA gives an exact number, threshold, or rule. No interpretation needed. | "150% risk weight" for all ADC exposures |
| Partially defined | The PRA provides a framework or conditions but leaves specific thresholds to the lender. | Valuation must be by an "independent valuer" (but no register or qualification specified) |
| Undefined | The PRA uses a qualitative term with no numerical guidance. The lender must define, document, and defend their own threshold. | "Substantial cash deposit" |
And one of four Mintstone coverage statuses:
| Status | Meaning |
|---|---|
| Live | Mintstone calculates, tracks, and alerts on this automatically from live project data. |
| Configurable | The lender sets their own threshold in Mintstone. The system then monitors against it. |
| Lender process | This is a credit or legal decision that belongs to the lender. Mintstone stores and timestamps the evidence but does not make the judgement. |
| Outside scope | Not relevant to ADC monitoring (e.g., applies to completed regulatory real estate only). |
3. The matrix: Article 124K requirements
These are the requirements that directly determine whether an ADC exposure can be classified at 100%.
| Requirement | PRA specificity | What the rulebook says | Evidence needed | Mintstone |
|---|---|---|---|---|
| Default risk weight | Prescribed | All ADC exposures: 150% (Art. 124K(1)) | Classification record showing 150% applied | Live |
| 100% exception: residential only | Prescribed | 100% available only for "land acquisition for the development and construction of residential real estate, or financing the development and construction of residential real estate" (Art. 124K(2)) | Property type classification. Commercial ADC stays at 150% regardless. | Live Property type gate: commercial locked at 150%, mixed-use requires ≥50% residential by GDV |
| Mixed-use split | Partially defined | Mixed real estate must be split into residential and commercial portions "according to the ratio of the values" (Art. 124(4)) | GDV split between residential and commercial portions | Configurable Residential portion threshold configurable per facility (default 50%) |
| Prudent underwriting standards | Undefined | "The exposure is subject to prudent underwriting standards" (Art. 124K(2)(a)). Only definition: "assess the ability of the borrower to repay" (Art. 124B(1)) | The lender's underwriting policy, applied consistently, with evidence that conditions are still met post-origination | Configurable Mintstone provides the ongoing evidence (SPI, CPI, covenants, equity, valuations). The underwriting policy itself is the lender's. |
| Legally binding contracts | Prescribed | "Legally binding pre-sale or pre-lease contracts" (Art. 124K(2)(b)(i)) | Exchanged contracts (sales) or executed AFLs (leases) | Live Pre-sale/pre-lease agreements tracked with type, status, exchange date |
| Substantial cash deposit | Undefined | "The purchaser or tenant has made a substantial cash deposit" (Art. 124K(2)(b)(i)). No percentage or amount defined. | Deposit amount per agreement, verified against a lender-defined threshold | Configurable Sale deposit: default 10% of purchase price. Lease deposit: default 3 months of annual rent. Both configurable per facility. |
| Deposit subject to forfeiture | Partially defined | "Subject to forfeiture if the contract is terminated" (Art. 124K(2)(b)(i)). Clear requirement, but no guidance on how to verify or what exceptions (e.g., sunset clauses) mean for this. | Forfeiture terms confirmed in each contract. Sunset clause dates tracked. | Lender process Mintstone flags sunset dates and tracks SPI against them. Contract review for forfeiture terms is a lender legal process. |
| Significant portion of total contracts | Undefined | "Amount to a significant portion of total contracts" (Art. 124K(2)(b)(i)). No percentage defined. | Pre-sale/pre-lease count as % of total units, measured against a lender-defined threshold | Configurable Default 50% of total units. Configurable per facility. Alerts when coverage drops below threshold. |
| Substantial equity at risk | Undefined | "The borrower has substantial equity at risk" (Art. 124K(2)(b)(ii)). No percentage or basis defined. | Equity contributed as % of GDV, measured against a lender-defined threshold, verified from actual cash flows | Live Equity from open banking (INVESTOR transactions vs GDV). Default 25% threshold (20% for public housing). Both configurable. |
Of the nine requirements above, three are fully prescribed, three are partially defined, and three are entirely undefined. The three undefined terms ("substantial deposit," "significant portion," "substantial equity") are the ones that determine whether a lender gets 100% or 150%. This is where lenders need documented thresholds, consistently applied, with evidence to back them up.
4. The matrix: valuation requirements (Article 124D)
124K(2)(a) explicitly includes "the valuation of any real estate used as security." This brings Article 124D into scope for ADC. These are the most prescriptive requirements in the framework.
| Requirement | PRA specificity | What the rulebook says | Evidence needed | Mintstone |
|---|---|---|---|---|
| New valuation at origination | Prescribed | "An institution shall obtain a valuation when it issues a new loan" (Art. 124D(4)) | RICS valuation report on file, dated at or near origination | Live Valuation upload with date, valuer, GDV. Flags if missing. |
| Revaluation on 10% decline | Prescribed | "If the institution estimates that the value of the property has decreased by more than 10% relative to the last qualifying valuation as a result of a broader decrease in market prices" (Art. 124D(5)(b)) | AVM or market data showing decline; updated RICS valuation obtained | Live AVM tracked via PropertyData against RICS baseline. 10% decline triggers revaluation recommendation alert. Watch threshold at 5%. |
| 3-year revaluation (large loans) | Prescribed | "Where the amount of the loan is more than GBP 2.6 million or 5% of the own funds of the institution, and three years have passed since the last qualifying valuation" (Art. 124D(5)(c)) | Valuation currency record; updated valuation before 3-year expiry | Live Days-to-valuation-expiry tracked. Default: 3 years. Watch/breach alerts configurable (default watch at 80% of interval). |
| 5-year revaluation (all loans) | Prescribed | "Five years have passed since the last qualifying valuation" (Art. 124D(5)(d)) | Valuation currency record | Live Covered by the same valuation currency monitoring. Configurable per facility. |
| Independent valuer | Partially defined | "An independent valuer who possesses the necessary qualifications, ability and experience" (Art. 124D(8)(a)) | Valuer name and qualifications on record. Independent of borrower. | Live Independent valuer flag tracked per valuation. Alerts if not set. |
| No price increase expectations | Prescribed | Valuation "excludes expectations on price increases" (Art. 124D(8)(b)) | Red Book valuation basis (Market Value, not "hope value") | Lender process This is a valuation methodology requirement. The RICS valuer is responsible. Mintstone stores the valuation but does not assess its methodology. |
| Not higher than market value | Prescribed | Valuation "is not higher than the market value" (Art. 124D(8)(c)) | RICS valuation at or below market value; AVM as cross-check | Live AVM tracked against RICS GDV. If RICS exceeds AVM significantly, this is flagged. |
| Frequent market monitoring | Undefined | "An institution shall monitor the market value of the property on a frequent basis" (Art. 124D(2)). "Frequent" is not defined. | Regular AVM checks or market comparables | Live AVM updated from PropertyData. BoE base rate, ONS HPI, and rent indices tracked. Continuous, not periodic. |
Article 124D gives more specific rules than any other part of the ADC framework. The 10% revaluation trigger, 3-year and 5-year frequency rules, and independent valuer requirement are all explicit. This is also the area where Mintstone has the deepest automated coverage, because the thresholds are defined by the PRA rather than left to the lender.
5. The matrix: ongoing monitoring
The PRA does not prescribe specific ongoing monitoring metrics for ADC exposures. But 124K(2)(a) says the exposure must be "subject to" prudent underwriting standards. Present tense. Not "was subject to at origination." This implies ongoing compliance.
The following are the operational metrics that evidence whether underwriting remains prudent across the life of a facility. None of these are prescribed by the PRA. All of them are what a supervisor would expect to see.
| Metric | PRA specificity | Why it matters for 124K | What to track | Mintstone |
|---|---|---|---|---|
| Schedule Performance Index (SPI) | Undefined | A project behind schedule may miss sunset dates (losing pre-sales), overrun on costs (consuming contingency), or stall entirely. Schedule performance is the earliest signal that the lender's exit is at risk. | SPI = earned value / planned value. Track against configurable watch and breach thresholds. | Live Calculated from work item statuses and dates. Defaults: watch 0.85, breach 0.70. Alerts on threshold crossings. |
| Cost Performance Index (CPI) | Undefined | Cost overruns consume contingency, then threaten borrower equity. CPI below 1.0 means the project is spending more than planned for the value delivered. Persistent CPI deterioration may trigger a reclassification if equity is eroded. | CPI = earned value / actual cost. Track against configurable thresholds. | Live Calculated from work item payments and budgets. Defaults: watch 0.90, breach 0.80. |
| LTV (Loan-to-Value) | Partially defined | Art. 124C defines LTV calculation for regulatory real estate. Not explicitly required for ADC, but fundamental to "prudent underwriting." Every lender tracks it. | Drawn amount / current GDV. Monitor against facility covenant. | Live Recalculated on every drawdown and valuation change. Configurable watch/breach per facility. |
| LTC (Loan-to-Cost) | Undefined | Measures lender exposure relative to total development cost. More relevant than LTV during construction because GDV is a future estimate. | Drawn amount / total development cost. Monitor against facility covenant. | Live Recalculated on every drawdown and budget change. Configurable watch/breach. |
| LTGDV (Loan-to-Gross Development Value) | Undefined | Facility drawn amount as % of GDV. Shows how much of the end value the lender has funded. | Drawn amount / GDV from active valuation. | Live Defaults: watch 58%, breach 65%. Configurable. |
| Cost overrun % | Undefined | Current total cost vs original appraisal. Overruns eat contingency first, then threaten equity. | Current budget vs original budget, expressed as %. | Live Tracked from work item budgets vs originals. Defaults: watch 8%, breach 15%. |
| Site activity | Undefined | A site with no activity may indicate project stall, contractor insolvency, or developer cash flow problems. All threaten the lender's position. | Days since last verified site evidence (photo, progress update). | Live Defaults: watch 14 days, breach 30 days. |
| Pre-sale/pre-lease coverage | Undefined | Directly relevant to condition (b)(i). Coverage can drop if buyers rescind, sunset clauses trigger, or contracts lapse. | Qualifying agreements as % of total units, tracked on every change. | Live Separate sale/lease evaluation. Alerts on coverage drops. Sunset dates tracked against SPI forecast. |
| Borrower equity position | Undefined | Directly relevant to condition (b)(ii). Equity can erode through cash withdrawals, cost overruns beyond contingency, or GDV decline. | Net equity contributed as % of GDV, verified from actual cash flows. | Live Open banking: INVESTOR transactions tracked in real time. Equity/GDV recalculated on every bank transaction and valuation change. |
| Days to completion | Undefined | Proximity to completion affects sunset clause risk, interest roll-up, and facility expiry. | Calendar days to projected completion date. | Live Defaults: watch 90 days, breach 30 days. |
6. The matrix: what is an ADC exposure? (Article 124A)
Before any of the above applies, the lender must first determine whether an exposure is ADC at all. This is less straightforward than it appears.
| Question | PRA specificity | What the rulebook says | Evidence needed | Mintstone |
|---|---|---|---|---|
| Is the property acquired/held for development and construction? | Partially defined | ADC if "acquired or is held for development and construction purposes" and works "not yet complete" (Art. 124A(1)(a)(i)-(ii)) | Loan purpose documentation. Property status (land, under construction, complete). | Lender process Initial classification is a credit decision. Mintstone tracks project status and flags when works are complete (triggering exit from ADC). |
| Are works complete? | Partially defined | Once development and construction is complete, the exposure moves to "regulatory real estate" (Art. 124A(1)(a)(ii)). But "complete" is not defined (practical completion? CPC? fully let?). | Practical completion certificate. Evidence of handover. | Lender process Mintstone tracks project status. The transition from ADC to regulatory real estate is triggered by status change and reclassifies the risk weight. |
| Is it a self-build? | Prescribed | Self-build exposures are explicitly "not ADC" (Art. 124A(1)(a)(iii)). They are regulatory real estate, valued at land value × 0.8. | Loan classification as self-build | Outside scope Self-build is not ADC and therefore outside Mintstone's ADC monitoring scope. |
| Is it a refurbishment? | Undefined | The rulebook does not mention "refurbishment." The test is purpose of acquisition: was the property "acquired or held for development and construction"? A light refurb of an existing building may not be ADC. A gut-and-convert may be. | Loan purpose, scope of works, whether property was acquired specifically for the works | Lender process This is a classification decision at origination. Mintstone monitors whichever classification the lender assigns. |
When a project reaches practical completion, it stops being ADC. If conditions are met, a £10m exposure at 150% could move to 35% risk weight (regulatory residential, not cash-flow dependent, LTV ≤50%). That releases approximately £920k of capital. Lenders should have a clear, auditable process for recognising this reclassification promptly rather than leaving exposures at 150% after works are finished.
7. Summary: prescribed vs undefined
Across all requirements relevant to ADC classification:
| Category | Prescribed (exact rules) | Partially defined | Undefined (lender judgement) |
|---|---|---|---|
| Risk weight and scope | 150% default; 100% residential only; self-build excluded | Mixed-use split; "complete" not defined | Refurbishment classification |
| Condition (a): prudent underwriting | (none) | (none) | "Prudent underwriting standards" (entire concept) |
| Condition (b)(i): pre-sales | "Legally binding" | "Subject to forfeiture" | "Substantial" deposit; "significant portion" |
| Condition (b)(ii): equity | (none) | (none) | "Substantial equity at risk" (entire concept) |
| Valuation | 10% revaluation trigger; 3yr/5yr frequency; independent valuer; no price increase expectations; not above market value | Valuer qualifications | "Frequent" market monitoring |
| Ongoing monitoring | (none prescribed specifically for ADC) | LTV calculation method (Art. 124C, for regulatory RE) | All other metrics: SPI, CPI, LTC, LTGDV, cost overrun, site activity, days to completion, equity tracking |
The pattern is clear: the PRA prescribes the consequences (150% if you fail) and the valuation rules (exact triggers and frequencies), but leaves the core underwriting conditions (prudent standards, substantial deposit, significant portion, substantial equity) entirely to the lender.
This is why documentation matters. A lender who can point to defined thresholds, applied consistently, monitored automatically, and evidenced with an audit trail, is in a materially stronger position than one relying on ad hoc judgements recorded in emails.
8. What Mintstone covers and what it does not
Mintstone is an evidence platform. It does not make credit decisions, set policy, or replace legal review. Here is the boundary:
What Mintstone does
- Calculates SPI, CPI, LTV, LTC, LTGDV, cost overrun, and equity position from live project data
- Tracks pre-sale and pre-lease coverage with separate deposit evaluation (% of price for sales, months of rent for leases)
- Verifies deposits from uploaded evidence with AI-assisted extraction and cross-checking
- Monitors borrower equity from classified open banking transactions in real time
- Tracks AVM against RICS baseline with automated revaluation triggers at 10% decline
- Monitors valuation currency (days since last RICS valuation) against 3-year and 5-year rules
- Applies property type gating (commercial locked at 150%, mixed-use threshold configurable)
- Reclassifies risk weight on every data change with full snapshot persistence
- Fires alerts via Telegram when any watch or breach threshold is crossed
- Generates one-click PRA audit reports with source-to-report data lineage
- Provides 16+ configurable covenant monitors, each with independent watch and breach levels
What the lender must do
- Define what "substantial deposit" means for their book (Mintstone provides a default of 10%/3 months, but the lender must own the number)
- Define what "significant portion" means (default 50%, but the lender must document why)
- Define what "substantial equity" means (default 25%/20%, same principle)
- Assess borrower ability to repay at origination (credit assessment, PG review)
- Review forfeiture terms in pre-sale and pre-lease contracts (legal process)
- Determine whether an exposure is ADC or regulatory real estate at origination
- Determine when "complete" means complete (practical completion, CPC, fully let)
- Commission RICS valuations when triggered
- Act on alerts and escalations (credit committee decisions)
Mintstone generates the evidence. The lender makes the decisions. When a supervisor asks "how did you classify this exposure?", the lender points to the policy (their document), the thresholds (configured in Mintstone), the data (calculated live from the project), and the audit trail (persisted with every classification). That is the complete answer.
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Mintstone tracks every metric in this matrix, live, across your ADC book, with configurable thresholds and full audit lineage.
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This paper is published by Mintstone Ltd for informational purposes only. It does not constitute legal, regulatory, or financial advice. The interpretation of PRA2026/1 presented here reflects Mintstone's reading of the published rulebook instrument. Lenders should obtain independent legal and regulatory advice before making capital classification decisions. Mintstone is not regulated by the FCA or PRA. The Prudent Underwriting Matrix is a suggested approach, not a regulatory requirement or industry standard.