I have a similar question, as it relates to ethereum gas fees.
If the fee is part of a buy, it seems pretty clear how to account for it: reduce the number of shares you get, & and some value to the ‘fee’ amount so the total purchase amount (USD or EUR) matches the amount you spent. Thus, the amount ‘lost’ to gas becomes fees. Likewise, for sale operations: account for the value lost to gas by inputting ‘fees.’
However, in other cases - i.e. spending ethereum on gas to send another erc20 token somewhere your ETH shares gets reduced, by an operation for an unrelated security (crypto). What’s the best way to account for that?
I was thinking of recording the gas as an Ethereum “Sell” for a price of $0.
Another option would be an Ethereum sell for the current market value, and then a ‘removal’ of currency for that same value - but that would imply realizing cap gains on the sale (aka paying tax on the sold amount), which actually results in the fee costing more, and would be inconsistent with the above: you don’t pay additional tax on the gas eth fees when buying/selling eth, it just increases your cost basis on buys & reduces your realized gain. Thus, I thought selling for $0 is the most logical. But I’d be interested in how others are dealing with this.