The treaty rate everyone gets right, and the three it hides

It is tax the payer deducts before sending interest abroad. America applies a statutory rate to US source income paid to foreign persons, which Publication 515 works through, and interest falls within that by default.

The treaty then displaces it. Article 11 makes interest taxable only in the country where the beneficial owner lives.

Interest arising in one country and beneficially owned by a resident of the other is taxable only in that other country. So a UK lender receiving American interest pays British tax on it and no American tax at all.

That is unusually generous as treaty articles go. Dividends keep a source-country rate, as our guide to dividend withholding explains, while ordinary interest does not. Both governments publish the convention and its supporting documents.

More than you might assume. The article covers income from debt-claims of every kind, whether or not a mortgage secures them, and whether or not they carry a right to share in the debtor's profits.

It names government securities, bonds and debentures specifically, including premiums or prizes attaching to them. It also sweeps in anything the source country taxes the same way as money lent.

Two things fall outside. Income dealt with by the dividends article is excluded, and so are penalty charges for late payment.

So check the instrument rather than its name. A payment labelled interest that participates in profits may still leave this article by a different door.

This is the exception that catches people. Where interest is determined by reference to the debtor's receipts, sales, income, profits or other cash flow, America may still tax it.

The reach is wider still. Interest set by reference to a change in the value of the debtor's property, or to a dividend or partnership distribution made to a related person, falls in the same place.

The rate is capped rather than removed. Such interest may be taxed at a rate not exceeding the rate the dividends article sets for ordinary portfolio dividends.

US interest withholding therefore depends on the formula, not on the headline rate. A loan at a fixed margin plus a revenue share carries two characters in one instrument.

The treaty draws a sensible boundary. An arrangement does not fall into the exception merely because the interest reduces if the relevant factors improve.

The mirror case is also excluded. Nor does it apply merely because the interest increases if those factors deteriorate.

So a ratchet that protects the lender is not the same as a profit share. The exception targets interest that behaves like equity.

A narrower provision deals with mortgage and asset securitisations. Where interest is paid on ownership interests in such a vehicle, the source country may tax it under its domestic law.

The charge is limited to the excess. It applies only to the extent the interest exceeds the return on comparable debt instruments, as that country's law specifies.

The article protects the beneficial owner rather than whoever happens to receive the money. Someone collecting interest as a nominee or an agent for another person does not qualify in their own right.

So look through the payment chain before claiming anything. A custodian holding for an underlying investor is not the person this article has in mind.

That distinction also explains the conduit rule below. Both aim at the same thing, which is treaty access for people the treaty was never written for.

The whole article switches off. Its provisions do not apply to interest paid under, or as part of, a conduit arrangement.

That is a complete exclusion rather than a rate adjustment. So an arrangement routing interest through Britain to reach the zero rate does not merely lose some relief; it loses the article.

So the ownership chain matters as much as the lending terms do. Treaty access is ultimately a question about who benefits.

Yes, and it moves the whole question. Where the beneficial owner carries on business in America through a permanent establishment, and the interest is attributable to it, the ordinary rule does not apply.

The business profits article takes over instead. So the interest joins the rest of the operation's profits, as our guide to permanent establishment sets out.

The treaty splits the payment. Where a special relationship between payer and beneficial owner pushes the interest above what they would have agreed at arm's length, the article applies only to the arm's length part.

The excess goes back to domestic law. Each country then taxes it under its own rules, with due regard to the rest of the convention.

So intra-group lending needs a defensible rate for this reason too, not only for transfer pricing.

Intra-group lending attracts more attention than third-party lending, for two reasons sitting in different places. The rate has to be defensible, and the interest has to be genuine interest.

US interest withholding can also turn on whether the arrangement is debt at all. A loan with no repayment terms, and no realistic expectation of repayment, starts to look like something else entirely.

So document the lending decision properly. The paperwork does more work here than the rate itself does.

Through paperwork given to the payer in advance. A UK company certifies its position on a W-8BEN-E, and the instructions set out what that certificate claims.

No form means the statutory rate. The payer has nothing to rely on, so it deducts and reports, and recovering the difference becomes a US filing exercise.

In our practice that is the commonest way a zero rate turns into a refund claim. The entitlement was there; the certificate was not.

Certificates do not last forever, and a lapsed one has the same effect as no certificate at all. US interest withholding simply resumes at the statutory rate.

So diarise the expiry alongside the loan's own dates. Long-dated lending outlives the paperwork protecting it, which is an avoidable way to lose the rate.

A zero rate does not mean silence. The withholding agent still files an information return, even where it deducted nothing because a treaty exempted the income.

You should therefore expect a statement. Our guide to Form 1042-S covers how to read it and what HMRC expects you to do with it.

In full, as foreign income. The treaty gives Britain the taxing right, so the whole amount enters your UK return rather than a reduced slice.

That is the trade. You lose nothing to American withholding and you keep the entire liability at home, which is usually the better outcome but not always the cheaper one.

Remember the timing difference too. The British tax year and the American calendar year rarely align, so one loan can straddle two returns.

No, the article speaks of a resident of a contracting state and makes no distinction by type. An individual lender sits in the same place as a corporate one on the ordinary rule.

The certificate differs, though. An individual gives the personal version of the form rather than the entity version, and the payer will usually say which it expects.

Still, the analysis underneath is identical. Beneficial ownership, the rate formula and any US presence decide the answer for either of them.

Take an illustrative case. A British company lends 2 million dollars to an unconnected American business at a fixed 7 per cent, documented and arm's length.

The interest is ordinary interest. With a certificate on file the payer deducts nothing, and the lender reports the full amount in Britain.

Now change one term. Make the rate 3 per cent plus a share of the borrower's annual revenue, and the revenue-linked element moves into the performance exception, where America may tax it within the capped rate.

Split the instrument in your records. Where part of the coupon is ordinary and part is revenue-linked, the two parts travel under different paragraphs.

The commonest is assuming the zero rate is automatic. It depends on a certificate reaching the payer before payment, and nothing applies it retrospectively.

The second is missing the performance exception on a participating loan, usually because the headline rule felt settled.

After those comes the group loan priced generously, where the excess above an arm's length rate quietly leaves the protection of the article.

First we read the loan terms rather than the label, because the rate formula decides which paragraph applies. Then we check the beneficial ownership and the absence of any US presence.

We also get the certificate to the payer in time, which is the step that actually delivers the rate. Start with our treaty relief service, or reach us through our contact page.