Self-employed across borders, without paying into two systems.
Freelance income crosses borders easily; the social security systems attached to it do not. Without the right certificate you can owe US self-employment tax and UK National Insurance on the same pound.
One income, two social security claims
The US-UK totalization agreement decides which country's system you pay into — but it only protects you with a certificate of coverage in hand. Meanwhile the income itself is reported on both returns, with credits flowing under the ordinary treaty rules.
- Certificates of coverage under the totalization agreement
- Schedule C and UK self-employment pages, aligned
- Estimated taxes and payments on account, both sides
- VAT and sales tax registration questions
The company question, answered with numbers
A UK limited company is often tax-efficient for a British contractor — and a CFC filing burden for an American one. Whether to incorporate, and where, depends on your citizenship and residence path. We run the numbers before you form anything.
What we typically handle for you
- Certificates of coverage under totalization
- Schedule C and UK self-employment pages, aligned
- Estimated taxes and payments on account
- Entity analysis: sole trader vs limited company
- VAT and sales tax registration questions
- Home-office and expense treatment both sides
- IR35 interaction for UK engagements
- Multi-client, multi-country income sourcing
The services that usually apply
Questions we get about this
It is often efficient in the UK, but a UK company owned by a US person brings controlled foreign company reporting and potentially GILTI.
That does not make it wrong, but the US cost has to be weighed rather than discovered later.
Commercially it is straightforward. The tax questions are where the work is performed, whether you have created a taxable presence, and any withholding at source.
Where you sit when you do the work usually matters more than where the client is.
Days worked in each country, where the work was performed, and invoices tied to those periods.
Both residence tests and any apportionment depend on exactly this, and it is trivial to keep and painful to rebuild.
Usually not. The US-UK totalisation agreement is designed to stop double social security, assigning you to one system.
A certificate of coverage is what actually evidences it, and it needs obtaining rather than assuming.
Often, but the definitions differ, and the UK also has its own employment status rules for engagements through a company.
Being treated one way in the UK does not settle how the IRS sees the same work.
It can apply to the earnings, but it does not remove US self-employment tax, which catches people out.
Where the totalisation agreement assigns you to the UK system, that is usually the cleaner answer.
Last reviewed . Thresholds and rates change annually — check figures against the current tax year before relying on them.
Contracting across the Atlantic?
We will confirm which system you pay into and what your structure actually costs on both sides.