Elena Prats is an audiovisual translator in Barcelona and works as an autónomo (self-employed). In May 2026 a production company in Los Angeles commissioned her to subtitle a series for 8,000 USD. Before paying, the production company's payments platform asked her to fill in a form called a W-8BEN. Elena had never heard of it; she saw it was a document from the US tax authority, with boxes about treaties and withholding rates, and she took fright: she did not know whether signing it committed her to anything in the United States, what number she had to enter or what would happen if she left it blank.
What it is and who asks for it
The W-8BEN is a form of the IRS, the tax authority of the United States. It is signed by an individual who is neither a US citizen nor a US resident and handed to whoever pays them, not to the IRS. With it, the payer documents that the beneficiary is foreign and, where relevant, that they are claiming the benefits of the double taxation treaty between their country and the United States.
For the payer it is a way of justifying to its own tax authority why it did not withhold, or why it withheld at a reduced rate. Without the form, its own rules may lead it to apply the default withholding, which is often set at 30 % of the payment. When that withholding applies, to which types of income and with what exceptions is a matter of US law: the client's adviser in the United States confirms it, not us.
There are variants that should not be confused:
| Form | Who signs it | Comment |
|---|---|---|
| W-8BEN | An individual who is not a US person | The case of a self-employed person like Elena |
| W-8BEN-E | A non-US entity | If you invoice through a Spanish company, not as a self-employed person |
| W-9 | A US person (citizen or resident) | Not for you if you are not American; signing it by mistake can generate tax reporting there in your name |
If you are a US citizen living in Spain, the W-8BEN is not your form; we deal with your situation in I am American and live in Spain.
How the form is organised
The W-8BEN has three parts. What follows describes its structure; if any box raises doubts about its effect in the United States, that is a question for an adviser there.
- Identification of the beneficial owner. Name, country of citizenship, permanent residence address (the one in Spain, not a PO box or a third party's address), mailing address if different, and identification numbers. This is where the box for the foreign tax identifying number appears, the tax number of your country of residence: for someone resident in Spain, their NIF or NIE (Spanish tax or foreigner identification number). The box for a US tax number is usually left empty if you do not have one.
- Claim of treaty benefits. You state the country of residence for treaty purposes (Spain) and, where appropriate, the article of the treaty being relied on, the withholding rate claimed and the type of income.
- Certification and signature. You declare on your own responsibility that the details are correct and that you are the beneficial owner of the income.
Signing the W-8BEN does not register you on any US register and does not, on its own, create filing obligations there. It is an information statement that stays with the payer.
What the treaty says from the Spanish side
The treaty between Spain and the United States forms part of Spanish law once published in the BOE, the Spanish official gazette, so we can explain its logic. Like most treaties signed by Spain, it reserves the profits of a business or professional activity to the country of residence of the person carrying it on, unless the activity is carried on in the other country through a permanent establishment or a fixed base. Elena subtitles in Barcelona, has no office in Los Angeles and has never set foot in the United States for this work. From the treaty's perspective, her income is taxed in Spain.
How US rules carry that over into the form, and whether in her case Part I is enough or Part II must be completed, is for the payer to settle with its adviser.
If tax is withheld anyway
Suppose the form arrives late and the payer applies 30 % withholding. With an assumed exchange rate of 1 € = 1.11 USD:
- Invoice: 8,000 USD, equivalent to 8,000 ÷ 1.11 = 7,207.21 €.
- Withholding: 8,000 × 30 % = 2,400 USD, equivalent to 2,162.16 €.
- Net payment: 5,600 USD.
- In Spain Elena declares as income the full invoice, 7,207.21 €, not the 5,600 USD received.
- Suppose that, once the proportional expenses are allocated, the net earnings from this commission are 6,500 € and that her effective average rate of IRPF (Spanish personal income tax) is 24.00 %.
- Cap on the double taxation deduction (art. 80 of the IRPF Law): 6,500 × 24 % = 1,560 €.
- Deduction in Spain: the lower of the amount paid (2,162.16 €) and the cap (1,560 €): 1,560 €.
- Not offset: 602.16 €, which could only be recovered by claiming a refund in the United States.
There is a further nuance. If the treaty did not allow the United States to tax that income, there is a risk that Hacienda, as the Spanish tax office is commonly known, will not even accept the deduction of the 1,560 €, because it would not be a tax payable in accordance with the treaty. That logic, and when it is better to claim at source, is in tax has been withheld abroad.
The details on the W-8BEN must be true. Giving as your permanent residence an address that is not yours, or claiming a treaty rate you are not entitled to, may have consequences there and here. If you are not sure about a box, it is better to ask the payer exactly what it needs than to improvise an answer.
Proof of residence you may be asked for later
Some payers, in addition to the W-8BEN, ask for a certificate of Spanish tax residence for treaty purposes. It is issued by the Agencia Tributaria, the Spanish tax agency, and requested through its online portal; we explain it in the guide to the tax residence certificate. Keep a copy of everything you hand over, together with the invoice and proof of payment, because that is what proves your situation if tax is withheld and you want to deduct it.
The form certifies a specific situation: your residence and your details on the date you signed. If you move to another country, change address or start invoicing through a company, the prudent course is to tell the payer, because what you signed will no longer be accurate and it may need a new document.
If you have several clients in the United States, or tax has been withheld and you do not know how much you recover here, you can send us the signed forms and the supporting documents through the form for self-employed people with international clients. The annual picture for people who invoice mainly to the United States is in I invoice clients in the United States.
The relationship between the forms foreign clients ask for, VAT and the income tax return in Spain is explained on the Salama Tax page on self-employed people with international clients.