W-9 (Oct 2018)

The W-9 object contains the form fields included in IRS Form W-9. The object appears in the data property of the form object where the formType is w9Oct2018. Properties are named so that they can be easily traced back to the official IRS form. You may want to compare the object to the official IRS Form W-9 for reference. Form W-9 includes space for one signature.

The signer is identified as the usPerson in the party property of the signature object.

The IRS revises tax forms from time to time. When forms are revised by official bodies, a new form type will be provided by Nextform, and the old form type will remain available, to avoid unexpected changes in fields and disruptions to integrations.

Example Object
  "name": "Robert Smith",
  "businessName": "Business, Inc.",
  "taxClassification": "llc",
  "llcClassification": "s",
  "otherClassification": null,
  "payeeExemption": null,
  "factaExemption": null,
  "country": "us",
  "address": "1234 Main St.",
  "city": "San Francisco",
  "state": "ca",
  "zip": "12345",
  "account": null,
  "ssn": "555555555",
  "ein": null,
  "hasWithholding": false


name string

The full name of the individual.

businessName string

The name of the business or entity.

taxClassification enum

An enum string corresponding to the checkboxes in line 3 of the form. Possible values include: individual, cCorp, sCorp, partnership, trustOrEstate, llc, orother.

llcClassification enum

If the taxClassification is llc then it is mandatory to include additional tax classification, corresponding to the three options next to the llc checkbox in the official tax form. Possible values include c for C-corporation, s for S-corporation, or p for Partnership.

otherClassification string

If the taxClassification is other then there is a mandatory field for additional details.

payeeExemption string

Payee exemption code, if any.

factaExemption string

FACTA exemption code, if any.

country string

The two-letter country code associated with the address. For form W-9 this is typically a United States address, however there are cases where non-U.S. addresses are allowed on form W-9, such as when a U.S. citizen is living abroad.

address string

The building or house number and street address.

city string

The name of the city.

state string

The state in lowercase two-letter postal code format, unless it is a non-U.S. address, in which it will be the full name of the state.

zip string

The 5 or 9-digit zip code as a string. 9-digit zip codes are normalized to include a dash.

account string

Optional field for account numbers. Note that if you would like to attach a user account number to the form, you may want to set the reference field on the session object rather than rely on the account field.

ssn string

The Social Security Number. May be blank if an Employer ID is provided. Otherwise it is mandatory.

ein string

The Employer ID Number. May be blank if a Social Security Number is provided. Otherwise it is mandatory.

hasWithholding boolean

A boolean value indicating whether or not the person is subject to backup withholding. If so, in Part II of the W-9, item #2 will be crossed out on the PDF that is generated.