Do 401k/IRA investments need to be in EFTs?

I know that after tax investments need to be in something like a Vanguard EFT to avoid higher taxes in the UK. However, I think that an IRA or 401K will be taxed in the UK as regular income and it doesn't matter how it's invested. Is that right?

I know that after tax investments need to be in something like a Vanguard EFT to avoid higher taxes in the UK. However, I think that an IRA or 401K will be taxed in the UK as regular income and it doesn't matter how it's invested. Is that right?

Correct.  I didn't change my target date funds inside my IRA. Outside the IRA (or 401k) their distributions would be subject to regular income tax by HMRC and not get the preferred tax rates that qualified dividends and capital gains would get.  Leaving the funds in the IRA, then when taking distributions it is all taxed as regular income, just as it is by the IRS.

Many thanks for the confirmation!