Hi, hope all is well!

I plan to treat as a nontaxable event. The ER 20 token was a tradeable digital representation of the genesis mainnet right to EOS tokens. And folks holding EOS on exchanges at the time have the same digital right that they did the day before/after the freeze.

And I hypothesize, if SEC ever treated EOS as a security, I presume they would link the pre-freeze ER 20 token and the post-freeze EOS mainnet token as the same asset, which would support the position.

Linking relevant article that you likely have seen in the past (and I note there is uncertainty at the time of the article): https://steemit.com/eos/@cryptotax/eos-token-swap-u-s-tax-considerations

The good news is, more brainpower is allocated to cryptocurrency and hopefully arguments emerge that support my common sense approach to this all. One research firm provided an interesting argument that chain splits are analogous to free samples and income is not realized until a taxpayer exhibits dominion & control over freely received assets. In RE: the EOS mainnet, if the EOS mainnet token was treated as income upon subsequent sale/disposition post-freeze, this doesn't address the issue of the cost basis locked up in the ER 20 token at the time of the freeze.

On a separate topic, did you see this? Pretty interesting: https://www.coindesk.com/ey-aims-to-make-it-easier-to-calculate-crypto-taxes-with-new-tool