All dividends of US-listed securities (regardless of whether the assets were bought through StashAway, or via your own broker) are subject to a 30% dividend withholding tax and the QII (Qualified Interest Income) rule. The latter rule applies to US-domiciled funds, especially US government bonds, of which some of the dividend withholding taxes can be claimed back.
The WHT is held at source and the rest of the dividends are redistributed back to your portfolio(s) and reinvested automatically. Additionally, these taxes are held at source and would have already been deducted from the dividend payments shown on your 'Transactions' tab.
Under the QII (Qualified Interest Income) rule, some of the dividend WHT from US domiciled funds (e.g. US government bonds) can be claimed back. Our broker will do this on your behalf and there is no involvement on the customer's part. We will do this once a year, and will notify you via email if you have any claimable WHT, which would be redistributed to your portfolio and automatically reinvested.
For further illustration, you may like to view this year's iShares report on QII ETFs. Some examples of QII ETFs that StashAway invests in are 20+ Year Treasury Bond (TLT) and 10-20 Year Treasury Bond (TLH).
Our investment team has given serious consideration to the 30% WHT and have considered other exchanges that have lower or no withholding tax. However, at the end of the day, we have decided to stay with US-listed securities despite the tax implications due to its deep liquidity, reputable fund management and most importantly, the lower tracking error. If you're interested to see a comparison between US-listed securities and foreign securities, here is an article that presents its case.