According to Investopedia at least [1], VOO and SPY are not considered substantially identical by the IRS:
> For example, if an investor sells the SPDR S&P 500 ETF (SPY) at a loss, they can immediately turn around and purchase the Vanguard S&P 500 ETF.
> The rationale is that the two S&P 500 ETFs have different fund managers, different expense ratios, may replicate the underlying index using a different methodology, and may have different levels of liquidity in the market. Presently, the IRS does not deem this type of transaction as involving substantially identical securities and so it is allowed, although this may be subject to change in the future as the practice becomes more widespread.
I wonder where that page gets its information. Its own quote links to an IRS document that doesn't seem to mention this case. Other places online recommend against it.
>There has been no IRS ruling on whether ETFs from two different companies that track the same index are considered substantially identical.
>Investment advisors and tax planners recommend against selling an index mutual fund from one fund company and buying another index fund tracking the same stock index from another mutual fund company.
>And while arguably swapping from index funds like SPY to IVV are almost certainly a wash sale abuse (or at least, a transaction that should trigger the wash sale rules)
If you look at Wealthfront's own documentation, when they do tax loss harvesting with ETFs, they find ETFs that track similar but not identical indexes:
Yup it sounds like a bit of a gray area for now. I think for most people it probably comes down to the way your broker reports the transaction on your 1099. I.e. if my broker reports it to the IRS as a "covered" loss, that's probably what I would use when filing my taxes.
