Gated two-step bank KYB chain under FinCEN CDD Rule 31 CFR 1010.230. Step 1 computes indirect natural-person beneficial ownership via recursive ownership-tier multiplication at the 25% threshold. Gate: if no beneficial owner is identified (is_beneficial_owner=false) the chain exits early. When a beneficial owner is found, Step 2 validates the W-8 series form structural consistency (form/Ch.3 compatibility, Ch.3/Ch.4 FATCA cross-check, 3-year validity, treaty rate) for withholding compliance. NOT the CTA/BOI domestic reporting rule. Synthetic entity IDs only — zero PII.
compute_cdd_ownership_25pct{
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"name": "compute_cdd_ownership_25pct",
"arguments": {
"ownership_tiers": [
{"entity_id": "HoldCo_A", "parent_id": null, "ownership_pct": 100},
{"entity_id": "EntityABC", "parent_id": "HoldCo_A", "ownership_pct": 50},
{"entity_id": "NP_ALPHA", "parent_id": "HoldCo_A", "ownership_pct": 25}
],
"natural_persons": ["NP_ALPHA"],
"target_entity_id": "HoldCo_A"
}
},
"id": 1
}
validate_w8_series_structural{
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"name": "validate_w8_series_structural",
"arguments": {
"form_type": "W-8BEN",
"chapter3_status": "Individual",
"chapter4_fatca_status": "",
"treaty_country": "GB",
"treaty_rate_pct": 15,
"income_type": "Dividend",
"form_date": "2024-03-15",
"reference_date": "2025-07-05"
}
},
"id": 2
}