W-8 validity and late-cure calculator

Enter the form, its signature date and what else is in the vendor file, and get the expiration date under the examiner's validity table, the separate treaty-claim clock, the late-W-8 cure rule for a given payment, and whether the vendor record itself would be flagged as possibly foreign.

Basis IRM 4.10.21.9.6, 4.10.21.9.7.3, 4.10.21.10.3.1 and Exhibits 4.10.21-1 and 4.10.21-3 (May 12, 2026); Treas. Reg. 1.1441-1(e)(4)Privacy runs in your browser; nothing you enter is sent or stored

1. The certificate

Form

Date signed

Treaty claim on the form?

Documentary evidence on file?

Passport, certificate of incorporation, etc.

U.S. indicia in your records?

U.S. address, phone, ID or birthplace; hold mail; standing instructions to a U.S. account.

Reported a payment on Form 1042-S every year?

W-8EXP tax-exempt organizations only.

2. The payment (for the late-W-8 test)

Date of the payment

Date you received the W-8

Blank if it was on file before the payment.

Test validity as of

Blank = today.

3. The vendor record (the examiner's first-pass screen)

TIN on the vendor record

EIN, SSN or ITIN; blank if none.

Country

State

ZIP or postal code

The rules the calculator applies

Validity. A W-8 is valid from the date signed "through December 31 of the third succeeding year"; the example given is a W-8BEN signed September 2019 expiring December 31, 2022. A W-8BEN or W-8BEN-E supported by documentary evidence, with no U.S. address, phone or standing instructions, is valid indefinitely, "but the portion ... that includes the treaty claim is subject to the general 3-year validity rule." W-8ECI: always three years. W-8EXP: indefinite for governments, central banks and international organizations; for a tax-exempt organization only "provided that the withholding agent reports on Form 1042-S at least one payment annually to the entity." W-8IMY: indefinite, but the certificates beneath it are not. Form 8233: one year. Documentary evidence: three years or its own expiration; non-renewable documents indefinitely (Exhibit 4.10.21-3).
Change in circumstances. Any form becomes invalid when the payer "knows or has reason to know" of a change; the payee has 30 days to report one, with a 90-day grace to re-document for chapter 4 (Exhibit 4.10.21-1).
U.S. indicia. A U.S. mailing address, a U.S. driver's license used as identification, a U.S. birthplace on a passport, a hold-mail instruction, a U.S. telephone number, or classification as a U.S. person in the payer's records makes the form unreliable regardless of its date (IRM 4.10.21.9.6).
Late W-8. A certificate received after the payment is acceptable for that payment if received within 30 days; with a signed affidavit under penalties of perjury that the information was accurate at the time of payment if received later; and with the affidavit plus documentary evidence if received more than one year after the payment (IRM 4.10.21.9.7.3). A late W-8ECI's affidavit must address inclusion on a U.S. return.
The vendor screen. The examiner's first pass flags an EIN beginning with 98, a TIN beginning with 9 (an ITIN), a country that is not the U.S. or is blank, a ZIP not in U.S. format, and a state that is not a U.S. state or is blank (IRM 4.10.21.10.3.1). A flag is a question, not a conclusion; the company "can establish" the payee is not foreign.

What it does not do

It does not validate the form's contents (status codes, limitation-on-benefits provision, TINs, GIIN against the FFI list), decide whether a payment is FDAP or U.S.-source, or apply the presumption rules to an undocumented payee; the exam guide covers those. Dates use the calendar-year rule; a form signed on December 31 expires three years later on the same day.