Double Taxation Relief Manual: Guidance by country: United States of America: Claims under the old agreement
Where the claimant is not a United States citizen, the claimant should be requested to supply
(a) a statement from the US tax authorities to the effect that the claimant is regarded as resident in the US for US tax purposes, or
(b) a copy of a completed US tax return covering the period of the claim showing that the taxpayer has been taxed in the US on his world-wide income (NB: simple completion of a US return is insufficient evidence since a non-resident may be required to complete a return if he has US source income).
Individuals who are not US citizens may become US tax residents by possession of a resident alien’s permit. This is issued by the US immigration authorities and colloquially known as a ‘green card’. Where a taxpayer claims to be resident in the US by virtue of his possession of a green card, sight of the green card alone should not be accepted as evidence of tax residence because the green card shows no date of issue and indeed the original may have been surrendered prior to the period under review. A taxpayer who claims to be resident in the US by virtue of his green card should be asked to produce a copy of his US tax return for the period covered by the claim.
If the US claimant is also resident in the UK during the period covered by the claim, see DT19862 below.