ISA and SIPP eligibility of US preferred stock

Whether you can hold a bitcoin treasury preferred inside a tax wrapper depends on two separate things. The first is HMRC's rules on what an ISA or pension may hold. The second is your provider's own policy on what it will offer. This guide covers the first and explains how to check the second. It is general information, not advice.

The ISA test for shares

HMRC's guidance for ISA managers, Stocks and shares investments for ISA managers (last updated 6 April 2026), says shares are qualifying investments if:

• they are issued by a company incorporated anywhere in the world; and
• they are either officially listed on a recognised stock exchange, or admitted to trading on a recognised stock exchange in the UK or the EEA.

The guidance does not treat preference shares separately. They are shares, so the same test applies. Nil-paid rights, warrants, futures and options are excluded.

"Recognised stock exchange" has the meaning in section 1005 of the Income Tax Act 2007. HMRC publishes tables of recognised exchanges, with guidance on which of each exchange's markets count as "listed". HMRC stresses that whether a security is listed "is a question of fact". The tables are guidance, not designations.

Nasdaq-listed series: STRF, STRC, STRK, STRD, SATA, SATS

HMRC's table of designated countries (updated 31 July 2026) says the following about the United States:

• any exchange registered with the SEC as a national securities exchange under section 6 of the Securities Exchange Act 1934 is a recognised stock exchange;
• NASDAQ Global, NASDAQ Global Select and NASDAQ Capital Market are listed as "listed" markets;
• OTC Bulletin Board and Pink Sheets are not recognised.

Strategy's STRF, STRC, STRK and STRD are registered on the Nasdaq Global Select Market. Strive's SATA and SATS are registered on the Nasdaq Global Market. On HMRC's published guidance, all six appear to meet the "officially listed on a recognised stock exchange" test.

Two points remain. First, your ISA manager must be willing to offer the security, and many platforms decide which US securities they carry. Second, holding US shares in an ISA does not change US withholding tax. The US does not recognise ISAs, so a W-8BEN is still needed. AJ Bell's W-8BEN page, for example, says the 15% treaty rate applies in its ISA and dealing accounts.

STRE on the Luxembourg Euro MTF

STRE is Strategy's euro-denominated series. Its prospectus supplement describes an application to list it on the Luxembourg Stock Exchange's Euro MTF market.

The same HMRC table recognises the Luxembourg Stock Exchange, which was designated on 21 February 1972. It classes the main Bourse de Luxembourg market as "listed" and the Euro MTF as "not listed". So STRE does not appear to meet the "officially listed" route as HMRC describes it.

The ISA rules also have a second route: admission to trading on a recognised stock exchange in the UK or EEA, and Luxembourg is in the EEA. HMRC's guidance does not say whether admission to the Euro MTF satisfies that route. 21DC cannot confirm STRE's ISA status. Ask your ISA manager how it classifies STRE.

MORE on the London Stock Exchange

The Smarter Web Company's MORE preferred shares were admitted on 14 October 2026 to the non-equity shares and non-voting equity shares category of the Official List and to trading on the Main Market of the London Stock Exchange (RNS, 14 October 2026).

HMRC's table of designated exchanges lists the London Stock Exchange Main Market as "listed". Its exceptions are the High Growth Segment, AIM and the Specialist Fund Market, none of which applies to MORE. On that basis, MORE appears to meet the ISA test. The company's 1 October 2026 update says the retail offer was made through intermediaries on the Winterflood Retail Access Platform. It does not say which wrappers those intermediaries accepted.

Metaplanet's MERCURY and MARS

As of 22 October 2026, neither series is listed on any exchange, as far as 21DC can confirm. Unlisted shares do not meet the "officially listed" test, so neither would currently qualify for an ISA by that route.

SIPPs work differently

There is no HMRC list of permitted SIPP investments. Registered pension schemes can, in principle, hold a wide range of assets. The tax rules penalise an investment-regulated pension scheme, which includes most SIPPs, if it acquires "taxable property". HMRC's Pensions Tax Manual at PTM125100 defines that as residential property and tangible moveable property. Shares, including preference shares listed on Nasdaq, Luxembourg or London, are neither.

In practice, the limit is the SIPP provider's own list of permitted investments and the range on its dealing platform. Some providers allow only securities listed on a recognised stock exchange; others allow more.

US withholding also works differently in a pension. Under Article 10(3)(b) of the UK–US treaty, dividends beneficially owned by a UK pension scheme are not taxed in the US, provided they are not derived from carrying on a business. Providers generally handle the documentation at scheme level. AJ Bell and interactive investor both say an individual W-8BEN is not needed for US holdings in their SIPPs.

Daily and weekly payments inside a wrapper

SATA and SATS pay on each business day, STRC pays semi-monthly and MORE pays weekly. Inside an ISA or SIPP, these payments arrive as cash in the account. They are not taxed in the UK and do not need to be reported. Platforms may convert each US dollar payment to sterling separately, so check the foreign exchange terms.

What to check before relying on this

• Your provider's list of eligible investments for the specific wrapper (ISA, Lifetime ISA, Junior ISA or SIPP). Do not rely on the fact that it offers the security in a dealing account.
• The market segment on which the series is listed: Nasdaq Global Select or Global Market, Luxembourg Euro MTF, or the London Stock Exchange Main Market.
• HMRC's current tables of recognised stock exchanges, which are updated from time to time.
• How your provider handles US withholding on ISA and SIPP holdings.
• For STRE, your ISA manager's written view on whether Euro MTF securities qualify.