Mortgage Agency Pricing and Eligibility

Gated three-step chain for agency mortgage decisioning. Step 1 checks the FHFA 2026 conforming loan limit to classify the loan as conforming, super-conforming, or jumbo. Step 2 verifies agency eligibility against the Fannie Mae DU / Freddie Mac LPA eligibility matrix including DTI caps, LTV/CLTV/HCLTV by occupancy and purpose, and multi-unit limits. A §21.4 gate at Step 2 exits immediately when the loan is ineligible for agency delivery, avoiding unnecessary LLPA computation. If eligible, Step 3 computes the full LLPA stack from the Fannie Mae public matrix (FICO by LTV base grid, purpose adjustments, FTHB AMI waiver).

OpenChainGraph · 3 Steps compliance mandate · §21.4 Gate Hash-Anchored §4 chain_depth:3 Client-Side · Zero PII

Chain Stages · 3 Steps · 1 Decision Gate (§21.4)

1 ROOT node

Conforming Loan Limit Check art-223-conforming-loan-limit

Conforming/super-conforming/jumbo classification feeds Step 2 agency eligibility check. FHFA 2026 baseline $806,500 (1-unit); high-cost ceiling $1,209,750; AK/HI/territories always receive ceiling.

MCP Call · check_conforming_loan_limit

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "check_conforming_loan_limit",
    "arguments": {
      "loan_amount": 650000,
      "units": 1,
      "state": "TX",
      "high_cost_county": false,
      "loan_program": "Conventional"
    }
  },
  "id": 1
}

↓

2 GATE node §21.4 gate

Agency Eligibility Matrix art-222-agency-eligibility-matrix

Agency eligibility verdict from DU/LPA grid. Checks DTI caps (50% DU/LPA), LTV/CLTV/HCLTV by occupancy and purpose, and multi-unit overlays. Gate exits chain when loan is ineligible; eligible loans proceed to LLPA pricing.

△ Gate: if /eligible_flag == "INELIGIBLE" → END | else → Step 3

MCP Call · check_agency_eligibility_matrix

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "check_agency_eligibility_matrix",
    "arguments": {
      "loan_purpose": "purchase",
      "occupancy": "primary",
      "units": 1,
      "ltv_pct": 80.0,
      "cltv_pct": 80.0,
      "hcltv_pct": 80.0,
      "dti_pct": 42.0,
      "au_system": "du"
    }
  },
  "id": 2
}

↓

3 TERMINAL node

LLPA Stack Calculator art-221-llpa-stack

LLPA pricing stack with table_version binding. Computes base FICO-by-LTV grid, purpose adjustments (cash-out, second-home, investment), condo and subordinate financing overlays, and FTHB AMI waiver. Only reached for agency-eligible loans. Table: FNM-LLPA-2025-11-01.

MCP Call · compute_llpa_stack

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "compute_llpa_stack",
    "arguments": {
      "fico": 740,
      "ltv_pct": 80.0,
      "loan_purpose": "purchase",
      "occupancy": "primary",
      "property_type": "single_family",
      "fthb": false,
      "ami_pct": 100
    }
  },
  "id": 3
}

Mortgage Agency Pricing and Eligibility