---
title: "W-8 Series Structural Validator"
method: POST
path: "/v1/tools/validate_w8_series_structural"
tags: ["TODO_TAGS_REVIEW", "TODO_AP2_EXPORT_REVIEW"]
---

# W-8 Series Structural Validator

`POST /v1/tools/validate_w8_series_structural`

## Request

- Base URL: `https://ainumbers.co`
- URL: `https://ainumbers.co/v1/tools/validate_w8_series_structural`
- Auth: none declared

Validates W-8 series form structural consistency for withholding tax compliance. Checks: form-type/Chapter 3 status compatibility (FORM_CH3_MISMATCH for W-8BEN-E + Individual mismatch etc.), Chapter 3/Chapter 4 FATCA cross-check (CH3_CH4_INCONSISTENT), 3-year validity window expiring Dec 31 of third year per Treas. Reg. 1.1441-1(e)(4)(ii) (FORM_EXPIRED), and treaty dividend rate against IRS Pub 901 table (TREATY_RATE_MISMATCH). Returns is_structurally_valid, violations[], validity_expiry_date, and days_until_expiry. Structural form codes only. No TIN. Zero PII by construction.

**Tool URL:** https://ainumbers.co/chaingraph/art-269-validate-w8-series-structural.html

## Request body

- object
  - `chapter3_status` string: type not evidenced by kernel source
  - `chapter4_fatca_status` string: type not evidenced by kernel source
  - `form_date` string: type not evidenced by kernel source
  - `form_type` string: type not evidenced by kernel source
  - `income_type` unknown
  - `reference_date` string: type not evidenced by kernel source
  - `treaty_country` unknown
  - `treaty_rate_pct` unknown

## Response `200`

Successful tool execution result

- object
  - `ch3_ch4_consistent` boolean
  - `chapter3_status` string
  - `chapter4_fatca_status` string
  - `days_until_expiry` integer
  - `form_ch3_compatible` boolean
  - `form_type` string
  - `is_structurally_valid` boolean
  - `not_legal_advice` string
  - `pii_note` string
  - `regulatory_basis` string
  - `statutory_withholding_rate_pct` integer
  - `table_source` string
  - `table_version` string
  - `treaty_country` string
  - `treaty_rate_expected` integer
  - `treaty_rate_pct` integer
  - `treaty_rate_valid` boolean
  - `validity_expiry_date` string
  - `validity_window_ok` boolean
  - `violation_count` integer
  - `violations` unknown[]
    - unknown

---

[API](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite.md) · [All operations](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite/llms.txt) · [OpenAPI document](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite/revisions/b462e4f5bb28?raw)