W-8 Implementation Guide

What is a W-8BEN and W-8BEN-E?

W-8BEN — the IRS form non-US individuals use to certify foreign status and, optionally, claim a reduced US withholding rate under an income tax treaty. A valid W-8BEN on file exempts the participant from 24% backup withholding on US-source income
W-8BEN-E — the W-8BEN counterpart for non-US entities. In addition to certifying foreign status, the entity declares its IRS tax classification (e.g., corporation, partnership, complex trust) and, if applicable, claims treaty benefits subject to a Limitation on Benefits provision

zerohash supports the generation of certified W-8BEN and W-8BEN-E forms via API. In the majority of cases, these two forms will be sufficient to cover your customer demographic, along with the W-9.

There are other variants of the W-8, such as the W-8IMY, W-8ECI, W-8EXP, and W-8CE. zerohash supports collection of these documents via document upload referenced in the section below.

W-8IMY — Participant is a non-US intermediary or flow-through entity (foreign partnership, simple trust, grantor trust, qualified intermediary, withholding foreign partnership/trust) that is passing US-source income through to its underlying beneficial owners
W-8ECI — Foreign participant claims their US-source income is effectively connected with the conduct of a US trade or business (and is therefore taxed on a net basis like a US person, not subject to 30% withholding)
W-8EXP — Entity is a foreign government, foreign central bank of issue, international organization, foreign tax-exempt organization, or foreign private foundation claiming the exemption available to those entities
W-8CE — Participant is a covered expatriate (a former US citizen or long-term green-card holder) electing how certain deferred compensation, tax-deferred accounts, or interests in non-grantor trusts are treated after expatriation

If you have any questions on what requirements apply to your specific customer demographic / how to classify users based on the above descriptions, reach out via your zerohash contact and we will assist you.

When should I collect it?

Any time you onboard a non-US person through zerohash's US flow. Participants onboarded through zerohash's EU or other non-US entities are governed by local tax documentation and do not need a W-form.

Individuals — collect a W-8BEN when the participant is not a US citizen, green-card holder, or US tax resident
Entities — collect a W-8BEN-E when the entity is not formed or organized under US law (foreign corporations, foreign partnerships, foreign trusts, etc.)

Do you already collect certified W-8 forms?

All you need to do is upload them via POST /participants/documents with the appropriate document type and you're done. Make sure to do this for pre-existing customers and on an ongoing basis for new customers.

zerohash supports all W-8 variants via document upload:

form_w8_ben
form_w8_ben_e
form_w8_imy
form_w8_eci
form_w8_exp
form_w8_ce

If the above doesn't apply to you, see the below instructions. If you're already onboarding customers via zerohash APIs, you're 90% there.

Collect the W-8 fields in your UX

Collect these new data points for the W-8BEN in your customer journey:

Foreign TIN — the participant's tax identification number issued by their country of tax residence
FTIN not legally required indicator — set if the participant's country of residence does not issue or require a foreign TIN
Mailing address — only if different from the residential address already captured via your normal participant onboarding
Treaty benefits claim — only if the participant is claiming reduced withholding under an income tax treaty:
- Treaty country
- Treaty article and paragraph
- Withholding rate claimed
- Type of income
- Residence certification — attestation that the participant is a tax resident of the named treaty country
- Additional conditions flag — indicator that any additional conditions in the treaty article have been met (if applicable)

In your UX, also surface a W-8BEN attestation checkbox confirming that the participant certifies foreign status, is not a US person, that any treaty claim is accurate, and will notify the platform within 30 days of any change in circumstances. For comprehensive attestation language, please reference the Certification section of the IRS W-8BEN template here.

For W-8BEN-E entities, in addition to all of the W-8BEN data points above, collect:

Tax classification

Treaty requirements certification — attestation that the entity meets the substantive requirements of the treaty provision being claimed
Limitation on Benefits (LOB) provision — the LOB article under which the entity qualifies for treaty benefits, selected from the standard set (see Claim of Tax Treaty Benefits section here)
- LOB "Other" article and paragraph — free-text article and paragraph of the LOB provision, required only when LOB = Other

Extend your attestation block on the W-8BEN-E to also cover the treaty-requirements certification. For comprehensive attestation language, reference the Certification section of the IRS W-8BEN-E template here.

Send the data to zerohash

Platforms can use the same endpoints they're already integrated with to provide the required tax data:

If you are onboarding net new individual participants

Example POST /participants/customers/new request:

{
  "first_name": "Jane",
  "last_name": "Doe",
  "email": "[email protected]",
  "address_one": "10 Downing St",
  "address_two": null,
  "city": "London",
  "zip": "SW1A 2AA",
  "jurisdiction_code": "GB",
  "phone_number": "442012345678",
  "date_of_birth": "1985-06-12",
  "id_number_type": "passport",
  "id_number": "987654321",
  "citizenship_code": "GB",
  "country": "GBR",
  "tax_id": null,
  "risk_rating": null,
  "signed_timestamp": 1747130096000,
  "kyc": "pass",
  "kyc_timestamp": 1747130096000,
  "onboarded_location": "GB",
  "sanction_screening": "pass",
  "sanction_screening_timestamp": 1747130096000,
  "idv": "pass",
  "employment_status": "full_time",
  "industry": "financial_services",
  "source_of_funds": "salary",
  "signed_agreements": [
    {
      "type": "user_agreement",
      "region": "uk",
      "signed_timestamp": 1747130096000
    }
  ],
  "mailing_address": {
    "address_one": "PO Box 99",
    "address_two": null,
    "city": "London",
    "state": null,
    "postal_code": "EC1A 1BB",
    "country": "GB"
  },
  "w_form_certification": 1747130096000,
  "signature": "signature_data",
  "signature_timestamp": 1747130096000,
  "is_w_form_certified": true,
  "w8_ben": {
    "ftin": "QQ123456C",
    "ftin_required": true,
    "reference_numbers": "ACME-USER-42",
    "treaty_claim": {
      "is_eligible": true,
      "country": "GB",
      "residence_certification": true,
      "income_type": "ROYALTIES_OTHER",
      "withholding_rate": "0",
      "article_paragraph": "Article 12, paragraph 1",
      "additional_conditions": false
    }
  }
}

If you are updating already-created individual participants

Example PATCH /participants/customers/{participant_code} request:

 {
    "is_w_form_certified": true,
    "w_form_certification": 1667504636159,
    "signature": "signature_data",
    "signature_timestamp": 1667504636159,
    "mailing_address": {
      "address_one": "PO Box 99",
      "address_two": null,
      "city": "London",
      "state": null,
      "postal_code": "EC1A 1BB",
      "country": "GB"
    },
    "w8_ben": {
      "ftin": "QQ123456C",
      "ftin_required": true,
      "reference_numbers": "ACME-USER-42",
      "treaty_claim": {
        "is_eligible": true,
        "country": "GB",
        "residence_certification": true,
        "income_type": "ROYALTIES_OTHER",
        "withholding_rate": "0",
        "article_paragraph": "Article 12, paragraph 1",
        "additional_conditions": false
      }
    }
  }

Entity Participants

If you are onboarding net new entity participants

Example POST /participants/entity/new request:

{
  "platform_code": "PLAT01",
  "entity_name": "Acme Family Trust",
  "legal_name": "Acme Family Trust",
  "contact_number": "442012345678",
  "website": "acme.co.uk",
  "date_established": "2005-04-15",
  "entity_type": "trust_estate",
  "address_one": "10 Downing St",
  "address_two": null,
  "city": "London",
  "postal_code": "SW1A 2AA",
  "tax_id": null,
  "id_issuing_authority": null,
  "risk_rating": null,
  "sanction_screening": "pass",
  "sanction_screening_timestamp": 1747130096000,
  "self_certification_timestamp": 1747130096000,
  "signed_timestamp": 1747130096000,
  "signed_agreements": [
    {
      "type": "user_agreement",
      "region": "uk",
      "signed_timestamp": 1747130096000
    }
  ],
  "submitter_email": "[email protected]",
  "submitter_first_name": "Jane",
  "submitter_last_name": "Doe",
  "submitter_title": "Trustee",
  "control_persons": [
    {
      "name": "Jane Doe",
      "email": "[email protected]",
      "address_one": "10 Downing St",
      "address_two": null,
      "city": "London",
      "postal_code": "SW1A 2AA",
      "jurisdiction_code": "GB",
      "date_of_birth": "1980-03-22",
      "phone_number": "442012345678",
      "citizenship_code": "GB",
      "tax_id": null,
      "id_number_type": "passport",
      "id_number": "987654321",
      "id_issuing_authority": null,
      "sanction_screening": "pass",
      "sanction_screening_timestamp": 1747130096000,
      "kyc": "pass",
      "kyc_timestamp": 1747130096000,
      "control_person": 1
    }
  ],
  "beneficial_owners": [
    {
      "name": "Jane Doe",
      "email": "[email protected]",
      "address_one": "10 Downing St",
      "address_two": null,
      "city": "London",
      "postal_code": "SW1A 2AA",
      "jurisdiction_code": "GB",
      "date_of_birth": "1980-03-22",
      "phone_number": "442012345678",
      "citizenship_code": "GB",
      "tax_id": null,
      "id_number_type": "passport",
      "id_number": "987654321",
      "id_issuing_authority": null,
      "sanction_screening": "pass",
      "sanction_screening_timestamp": 1747130096000,
      "kyc": "pass",
      "kyc_timestamp": 1747130096000,
      "beneficial_owner": 1,
      "role": "Trustee"
    }
  ],
  "incorporation_address": {
    "address_one": "10 Downing St",
    "address_two": null,
    "city": "London",
    "jurisdiction_code": "GB",
    "postal_code": "SW1A 2AA"
  },
  "mailing_address": {
    "address_one": "PO Box 99",
    "address_two": null,
    "city": "London",
    "state": null,
    "postal_code": "EC1A 1BB",
    "country": "GB"
  },
  "is_w_form_certified": true,
  "w_form_certification": 1747130096000,
  "signature": "signature_data",
  "signature_timestamp": 1747130096000,
  "jurisdiction_code": "GB",
  "w8_ben_e": {
    "tax_classification": "COMPLEX_TRUST",
    "ftin": "GB987654321",
    "ftin_required": true,
    "reference_numbers": "ACME-TRUST-1",
    "treaty_claim": {
      "is_eligible": false,
      "country": null,
      "residence_certification": false,
      "requirements_certification": false,
      "limitation_on_benefits": null,
      "limitation_on_benefits_other": null,
      "income_type": null,
      "withholding_rate": null,
      "article_paragraph": null,
      "additional_conditions": false
    }
  }
}

If you are updating already-created entity participants

Example PATCH /participants/entity/{participant_code} request:

{
  "is_w_form_certified": true,
  "w_form_certification": 1667504636159,
  "signature": "signature_data",
  "signature_timestamp": 1667504636159,
  "mailing_address": {
    "address_one": "PO Box 99",
    "address_two": null,
    "city": "London",
    "state": null,
    "postal_code": "EC1A 1BB",
    "country": "GB"
  },
  "w8_ben_e": {
    "tax_classification": "COMPLEX_TRUST",
    "ftin": "GB123456789",
    "ftin_required": true,
    "reference_numbers": "ACME-ENTITY-7",
    "treaty_claim": {
      "is_eligible": true,
      "country": "GB",
      "residence_certification": true,
      "requirements_certification": true,
      "limitation_on_benefits": "PUBLICLY_TRADED_CORPORATION",
      "limitation_on_benefits_other": null,
      "income_type": "BUSINESS_PROFITS",
      "withholding_rate": "0",
      "article_paragraph": "Article 7, paragraph 1",
      "additional_conditions": false
    }
  }
}

Send account updates as you do today

If a user updates their tax info later, just update their participant record with either the PATCH /participants/customers/{participant_code} for natural persons or PATCH /participants/entity/{participant_code} for non-natural persons. zerohash handles re-certification on our side.

What you need to know about W-8 Certification

Always pair certification with a timestamp

Whenever you send is_w_form_certified, send w_form_certification (the time the user attested) alongside it. Same for signature and signature_timestamp

Treaty claims are optional

Most foreign users don't claim treaty benefits. Leave treaty_claim.is_eligible as false (and the rest of the treaty block blank) unless the user qualifies under a specific income tax treaty article. For entities claiming benefits, limitation_on_benefits and requirements_certification are also required

Tax classification is required for entities

Every W-8BEN-E must declare a tax_classification for zerohash to properly generate a certified W-8BEN-E

W-8s expire after three calendar years

Unlike W-9, a W-8 is valid only through December 31 of the third year after signing. Re-collect and PATCH a fresh form before expiry — zerohash treats expired W-8s as absent and applies 24% backup withholding

When anything changes, just send an update

In the event of a name change, address change, country-of-residence change, treaty status change, or re-certification, PATCH the participant endpoint with the new values. zerohash handles re-validation