Here is the text which I extracted from the tax treaties for discussions with my tax advisors.
Please note that you need to discuss with your financial adviosrs as to their interpretation of this information along with the resulting impact on any taxes owed in either juristisdiction.
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Extracted information from tax treaty document available on webpage:
Tax treaties and related documents between the UK and USA.
https://www.gov.uk/government/publications/usa-tax-treatiesUnder Article 3 General Definitions:
Paragraph 1, sub-paragraph (o)
o) the term “pension scheme” means any plan, scheme, fund, trust or other arrangement established in a Contracting State which is:
(i) generally exempt from income taxation in that State; and
(ii) operated principally to administer or provide pension or retirement benefits or to earn income for the benefit of one or more such arrangements.
Article 17 describes treatment of lump-sum payment from a pension scheme:
ARTICLE 17 Pensions, social security, annuities, alimony, and child support
1.(a) Pensions and other similar remuneration beneficially owned by a resident of a Contracting State shall be taxable only in that State.
(b) Notwithstanding sub-paragraph a) of this paragraph, the amount of any such pension or remuneration paid from a pension scheme established in the other Contracting State that would be exempt from taxation in that other State if the beneficial owner were a resident thereof shall be exempt from taxation in the first-mentioned State.
2. Notwithstanding the provisions of paragraph 1 of this Article, a lump-sum payment derived from a pension scheme established in a Contracting State and beneficially owned by a resident of the other Contracting State shall be taxable only in the first-mentioned State.
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To clarify which “State” is which, my reading of this reads as:
A lump-sum payment derived from a pension scheme established in the US and beneficially owned by a resident of the UK shall be taxable only in the US.
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Under “Exchange of Notes” is clarification as to “pension scheme” definition.
With reference to sub-paragraph (o) of paragraph 1 of Article 3 (General Definitions):
it is understood that pension schemes shall include the following and any identical or
substantially similar schemes which are established pursuant to legislation introduced
after the date of signature of the Convention:
(a) under the law of the United Kingdom, employment-related arrangements
(other than a social security scheme) approved as retirement benefit schemes
for the purposes of Chapter I of Part XIV of the Income and Corporation
Taxes Act 1988, and personal pension schemes approved under Chapter IV of
Part XIV of that Act; and
(b) under the law of the United States, qualified plans under section 401(a) of
the Internal Revenue Code, individual retirement plans (including individual
retirement plans that are part of a simplified employee pension plan that
satisfies section 408(k), individual retirement accounts, individual retirement
annuities, section 408(p) accounts, and Roth IRAs under section 408A),
section 403(a) qualified annuity plans, and section 403(b) plans.