Ethereum vs Ethereum Classic: The Split That Came From a Single Contested Decision
How one hack and one controversial reversal in 2016 created two separate chains that still exist today, and what each one has stood for ever since.
By Firoz Khan|3 August 2026|Updated 11 October 2026|3 min read
Ethereum and Ethereum Classic share the exact same history up to a single point in 2016, a hack, and a community decision about how to respond to it, that split what had been one chain into two permanently separate ones, each continuing under a different philosophy from that moment forward.
The DAO hack that triggered the split
The DAO, an early and prominent investment DAO built on Ethereum, was exploited in 2016, with an attacker draining a substantial share of its pooled funds through a flaw in its smart contract code. The Ethereum community faced a genuinely difficult choice: accept the loss as the unfortunate but immutable outcome of how the code executed, or intervene to reverse it.
The attack took place on 20 July 2016, and the attacker took over 3.6 million ETH. The hard fork moved the stolen funds to a recovery contract. Some miners refused to fork, because the incident was not a defect in the protocol itself, and they went on to form Ethereum Classic.
The hard fork that reversed the hack
The majority of the community chose to implement a hard fork that effectively reversed the hack's effects, moving the drained funds to a recovery contract. This new, forked chain continued as what's now known simply as Ethereum, the one virtually everyone means today when they say the name.
Ethereum Classic: the chain that refused to reverse it
A minority of the community rejected the intervention on principle, arguing that reversing a transaction, however unwelcome its outcome, violated the core promise of an immutable, unstoppable ledger. This group continued on the original, unaltered chain, which became Ethereum Classic, still running today with 'code is law' as its defining philosophy.
Why the two have diverged so sharply since
Ethereum went on to become the dominant smart contract platform, switching to proof of stake and hosting the overwhelming majority of DeFi and NFT activity. Ethereum Classic has continued on proof of work with a far smaller ecosystem and market capitalisation, valued today primarily by holders who specifically prioritise its immutability principle over Ethereum's greater practical scale and adoption.
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How supply policy differs
Ethereum Classic has a stated limit on supply. ECIP-1017, the improvement proposal on its monetary policy, introduced an upper bound on the total number of ETC and a method of reducing issuance over time. That sets it apart in design terms from chains with no upper bound, and it is one reason some holders describe it as Bitcoin-like.
The same address on two chains
Both chains share their history until the fork, so anyone holding ETH when the split happened ended up with a matching balance of ETC. The same address works on each chain, but a transaction on one does not appear on the other, so be careful which network you are sending on.
What has happened to each since
Ethereum moved to proof of stake on 15 September 2022, and ethereum.org puts the fall in its energy consumption at about 99.95%. Ethereum Classic stayed on proof of work. It has also had security problems specific to that model: in August 2020 it suffered three 51% attacks, reported to have used rented mining power, and it responded with protocol and client changes, including the Thanos hard fork, which introduced its Etchash mining algorithm. A network with less mining power behind it is cheaper to attack.
Holding one or both in the UK
They are separate tokens, and for Capital Gains Tax HMRC treats each type of token as its own pool. If you held ETH when a contentious fork occurred, HMRC's guidance on forks says the new tokens are not treated as income, the fork itself is not a disposal, and the new tokens go into their own pool, with the cost split between the two pools on a just and reasonable basis. Selling one for the other is a disposal. The FCA says crypto is largely unregulated in the UK and that you should be prepared to lose all the money you put in.
Questions people ask
- Which one is the real Ethereum? Both continue the same early history. What most people mean by Ethereum today is the chain that carried out the fork, with ETH as its token.
- Does "code is law" make Ethereum Classic safer? It makes it a different bet. It did not prevent the 51% attacks of 2020 described above.
- Can I hold both? They are separate tokens, each with its own pool for UK Capital Gains Tax.
Where to read more
- Proof of work vs proof of stake: why the two chains secure themselves differently
- Crypto forks explained: soft forks, hard forks and how they are taxed
- Ethereum's Pectra upgrade explained: recent Ethereum changes
- Crypto taxes in the UK: pooling and forks
A reminder
The FCA risk warning still applies to higher-risk crypto content. Always assess how much risk you are willing to take before buying.
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