Your Agency Has a US Client. Now What?

You've landed a US client. Maybe it's a New York ad agency outsourcing creative work. Maybe it's a San Francisco tech company paying you for SEO. The money hits your UK business bank account, and you think "great, that's straightforward."

It is not straightforward. Not by a long shot.

Without the right paperwork and structure, the IRS can take a cut of that income. And HMRC can take a cut too. That is double taxation on US client income for your agency, and it can cost you anywhere from 15% to 30% of the revenue you earned from that client.

As ICAEW qualified accountants working exclusively with agency founders, we see this issue crop up regularly. The good news is that the US-UK Double Taxation Treaty exists specifically to prevent this. But you have to know how to use it. You cannot just assume it applies.

What Double Taxation Actually Means for Your Agency

Double taxation happens when two countries claim the right to tax the same income. Your agency is UK-resident, so HMRC taxes your worldwide profits. But the US also taxes income "sourced" in the US. If you perform work for a US client, the IRS can argue that income is US-source and demand withholding tax.

The standard US withholding rate on payments to foreign businesses is 30%. So a US client paying you £50,000 could legally withhold £15,000 and send it to the IRS. You then declare the full £50,000 to HMRC, pay UK corporation tax on it, and you have effectively paid tax twice on the same money.

That is the nightmare scenario. Here is how you stop it.

The Treaty Rate: 0% Withholding on Business Profits

The US-UK Double Taxation Treaty reduces the withholding rate on business profits to 0%. But only if you meet the conditions.

Article 7 of the treaty says that business profits of a UK resident company are only taxable in the UK, unless you have a "permanent establishment" in the US. A permanent establishment means a fixed place of business in the US, like an office, a branch, or even a home office you work from regularly. It can also include a dependent agent who concludes contracts on your behalf in the US.

If you do not have a permanent establishment in the US, the treaty says the US cannot tax your business profits. Full stop. The withholding rate drops to 0%.

But the IRS does not apply this automatically. You have to claim it.

Form W-8BEN-E: The One Document That Saves You Thousands

To claim the 0% withholding rate, your US client needs a completed Form W-8BEN-E from you before they make the first payment. This is a certificate of foreign status and beneficial ownership. It tells the US client (and the IRS) that you are a UK company entitled to treaty benefits.

Without a W-8BEN-E on file, your US client is legally required to withhold 30% and send it to the IRS. Most US companies know this. They will ask you for the form. If they do not, you should send it to them proactively.

The form asks for:

  • Your UK company name and address
  • Your UK tax identification number (your company's UTR)
  • A statement that you are the beneficial owner of the income
  • The specific treaty article you are claiming (Article 7 for business profits)
  • A certification that you do not have a permanent establishment in the US

You sign it, date it, and it is valid for three calendar years. One form covers all payments from that US client for three years. It is that simple.

If you have multiple US clients, each one needs their own W-8BEN-E. There is no central filing with the IRS. The form stays with the client's records.

What Happens if Withholding Was Already Taken

Maybe you already invoiced a US client and they withheld 30%. You are not stuck. You have two options.

Option one: Claim a refund from the IRS. You file Form 1120-F (for corporations) or a simplified refund claim using Form 8802 to get a certificate of residence, then Form 8833 to claim the treaty position. This takes months. The IRS is not quick. But it works.

Option two: Claim foreign tax credit relief in the UK. HMRC allows you to offset the US tax paid against your UK corporation tax liability on the same income. You report the US tax as a credit on your CT600 corporation tax return. This does not get your cash back from the IRS, but it stops you paying UK tax on money already taxed in the US.

Option one is better because you get the actual cash. But option two is faster and simpler if the amounts are small.

When the Treaty Does Not Apply: US Withholding on Royalties and Services

The 0% treaty rate applies to business profits. But some agency income is classified differently under US tax law.

Royalties are a common one. If you license software, code, or creative assets to a US client and they pay you ongoing royalties, the US withholding rate under the treaty is 0% for most royalties, but the classification matters. If the IRS reclassifies your service income as a royalty, you could face different treatment.

Services performed in the US are another trap. If you fly to New York for two weeks to deliver a project on-site, you may have created a US tax presence. The IRS can argue you have a permanent establishment if you spend more than 30 days in the US in any 12-month period performing services. Stay under that threshold, and you are generally safe.

If you have a US office, a US bank account, or a US employee, you almost certainly have a permanent establishment. At that point, you need US tax advice, not just UK advice. The treaty will not protect you from US tax on income attributable to that US presence.

Structuring Your Agency to Avoid Double Taxation Long-Term

The W-8BEN-E is a short-term fix. If US clients become a significant part of your revenue, you need a longer-term structure.

Option A: Keep everything in your UK company. This works if you have no US presence. File the W-8BEN-E with each client. Keep a log of your days spent in the US (if any). Use a UK accountant who understands the treaty. This is the simplest approach for agencies where US clients are 20-30% of revenue.

Option B: Set up a US subsidiary or branch. If US revenue exceeds £200k-£300k and you have US staff, a US entity makes sense. You incorporate a US LLC or C-corp, invoice US clients from that entity, and pay US tax on that income. The UK company receives dividends or management fees from the US entity. This is more complex but gives you a clean tax position in both countries.

Option C: Use a US sales agent or partner. If you work through a US-based agent who finds clients for you, be careful. If that agent has authority to conclude contracts on your behalf, they may create a permanent establishment for you in the US. Structure the arrangement so they are an independent agent, not a dependent agent. Independent agents work for multiple principals and do not bind you to contracts. Dependent agents do.

We have seen agencies accidentally create a US permanent establishment by hiring a US-based "sales rep" who signs contracts on their behalf. That is an expensive mistake. Get advice before you hire anyone in the US.

VAT and Sales Tax: The Other Tax Trap

Double taxation is not just about income tax. US sales tax can also apply if you sell digital services to US consumers. But for B2B services (agency selling to a US business), sales tax is generally not an issue. US businesses self-assess use tax on services they buy from overseas providers.

For UK VAT, exporting services to a US client is outside the scope of UK VAT. You do not charge VAT on the invoice. You do not include it in your VAT return as output tax. But you can still reclaim VAT on costs related to that US work, provided you have the right evidence.

This is where good bookkeeping matters. If you use Xero or QuickBooks, tag US client income with a separate tracking category so your accountant can review the treaty position easily at year-end.

Real Numbers: What This Looks Like for a Typical Agency

Let's say your digital agency turns over £400k per year. £80k of that comes from a US client in New York. You invoice them quarterly at £20k per quarter.

Without a W-8BEN-E on file, the US client withholds 30%: £6,000 per quarter. Over the year, that is £24,000 sitting with the IRS. You then pay UK corporation tax at 19% on the full £80k, which is £15,200. Total tax paid: £24,000 (US) plus £15,200 (UK) = £39,200 on £80k of income. Effective tax rate: 49%.

With a W-8BEN-E in place, the US client withholds nothing. You pay UK corporation tax at 19% on the £80k: £15,200. Effective tax rate: 19%. You keep an extra £24,000 in your business.

That is the difference a single form makes.

What to Do Right Now

If you have a US client today and have not given them a W-8BEN-E, send it this week. Download the form from the IRS website, fill it in, sign it, and email it to your client's accounts payable team. Ask them to confirm they have it on file.

If you have already been paid and tax was withheld, gather the evidence. Get the withholding certificate from your client. Speak to your accountant about whether to file a refund claim with the IRS or claim foreign tax credit relief in the UK.

If you are planning to win US clients, build the W-8BEN-E into your onboarding process. Every new US client gets the form before the first invoice. Make it standard procedure, not an afterthought.

And if your US revenue is growing, have a conversation with your accountant about whether a US entity makes sense. That decision depends on your revenue level, your US presence, and your long-term plans. It is not a decision to make alone.

At Agency Founder Finance, we are ICAEW qualified accountants who work exclusively with agency founders. We help agencies like yours structure cross-border income correctly, avoid double taxation, and keep more of what you earn. If you want to discuss your specific situation, get in touch.