This thread appears around eight years old and to me it is still as relevant as when it was written so I think it's time to re-activate. I hope it pops to the top so others having the same experience with reporting US capital gains on mutual funds to HMRC can contribute. Such a confusing area.
As background, I'm a dual US-UK citizen residing in the UK. I sold US Vanguard mutual funds in 2021. Despite having a specialist tax preparer for both my US and UK taxes, I have struggled to crack how to report capital gains from mutual funds in a Vanguard brokerage account to HMRC.
I just spent way too much of my winter leave speaking with Vanguard, HMRC, and my tax advisors - I reckon around eight hours dealing with this at this point despite paying premium for specialist advice.
Anyway, as the posters above point out, the 1099-DIV provided by Vanguard US does not appear to be helpful for the HMRC because the date of acquisition is stated as "various". My UK tax expert called the 1099 "useless" and when Vanguard was not able to supply exact versions of the various acquisition dates called them "lazy". My advisor also told me that I will be liable for fines and penalties if I do not provide the acquisition dates, which Vanguard cannot seem to give me. Needless to say I have already hired a new UK tax advisor, hoping for better luck next time around.
A HMRC technical expert called me back at 8:50am this morning. Out of my jet lagged slumber I awoke to an insistence from them that US Vanguard could of course tell me the acquisition dates of all my shares. And that HMRC have never encountered this problem before. Which I find very hard to believe, especially given the above discussion.
It is baffling to me that HMRC keep insisting for detail that US Vanguard repeatedly says they do not provide. Surely HMRC have experience with international capital gains.Therefore HMRC can appreciate requesting information that is not usually recorded in the respective country for that tax
system will be non standard and therefore an issue. No wonder some people make errors on their tax returns.
Finally, the HMRC expert advises that I can in fact use the dates I put money into Vanguard to make transactions as the date of acquisition and - unbelievably - ignore the dates of the re-investments. The HMRC expert also says that I do not need to match up the dates I sold the mutual funds to the exact dates they were purchased. And that if my UK tax advisor has any issues with this they can call their dedicated advisor line. So, seemingly, I can just look at my bank account to see what I bought versus what I took out, using the dates on my bank account, and go from there.
I await my completed tax documents from my UK tax advisor. I have very little hope for an end to this ordeal. I am happy to pay but HMRC do not seem to be able to tell me how much they want.