How to Do Ethereum, Polygon and Arbitrum Taxes: Every EVM Chain in One Guide

Overview

Ethereum set the template that most of the industry now runs on. Polygon, Arbitrum, Avalanche, Linea and a long list of others are EVM chains: separate networks that run the same kind of software, use the same 0x address format, and behave the same way. The good news is that one set of tax rules covers all of them. The bad news is that one address having activity on several of them is the most common reason a crypto tax report is incomplete.

This guide covers the whole family at once: which networks can be imported, what is taxable on any of them, how gas, bridges and airdrops are read, and the review every EVM import needs.

Fourteen Networks, One Address

Because the EVM chains share an address format and a key scheme, the address you use on Ethereum is also your address on Polygon, Arbitrum and every other EVM network. Nothing has to be created; the moment you switch network in your wallet, the same address is there, empty until you use it.

CryptoTaxBridge imports these networks:

Network	Gas paid in
Ethereum	ETH
Polygon	POL
Arbitrum One	ETH
Linea	ETH
Gnosis	xDAI
Avalanche	AVAX
Blast	ETH
Mantle	MNT
Sonic	S
Unichain	ETH
opBNB	BNB
Berachain	BERA
Taiko	ETH
World Chain	ETH

Each is a separate import, because each is a separate ledger. Copy your address once and import it on every network you have used. A quick way to find out which that is: paste the address into a multi-chain portfolio tracker or a wallet like Rabby, which lists the chains where it has activity.

BNB Smart Chain, Base and OP Mainnet are not on the list yet. If you used them, that part of your history has to wait for support; the rest of the record can be built in the meantime.

Import an EVM address

What Is Taxable on an EVM Chain

The rules are the same on every network:

Swapping is a disposal. Trading one token for another on Uniswap, Aerodrome, Trader Joe or any other decentralised exchange is a disposal of the token you gave and an acquisition of the token you received, at that day's values. HMRC's guidance lists exchanging one cryptoasset for another as a disposal, and the IRS treats it the same way. No fiat has to be involved.

Selling NFTs is a disposal. Buying one is an acquisition at what you paid plus gas.

Receiving tokens for something is income. Staking rewards, liquidity mining rewards, protocol incentives and airdrops earned by doing something are generally income at their value when received, and that value becomes their cost basis. Each reward is its own receipt with its own date.

Transfers between your own addresses and networks are not disposals. Sending ETH from your wallet to your exchange account, or from Ethereum to Arbitrum through a bridge, leaves you owning the same thing. But the record only sees a transfer if both sides are imported; otherwise it sees a withdrawal to nowhere and, elsewhere, a deposit from nowhere.

Paying for something in crypto is a disposal. The token you spent was sold at its value that day.

Gas Is a Cost, and Also a Small Disposal

Every EVM transaction pays gas in the network's own coin. Two things happen at once: you have disposed of a small amount of that coin, and you have paid a cost that attaches to whatever the transaction did.

HMRC lists transaction fees for getting a transaction onto the ledger among the allowable costs of a disposal, so gas paid on a sale reduces the gain, and gas paid on a purchase increases the cost basis. Most other jurisdictions reach the same answer. The exceptions are gas on transactions that are not acquisitions or disposals of anything — approvals, failed transactions, transfers to yourself — where treatment differs by country. Are crypto gas fees tax deductible goes through each case.

On L2s gas is cents. On Ethereum mainnet over a busy year it can be a meaningful amount, and either way the import records every fee so the question can be answered properly rather than estimated.

Review gas fees

Bridges

Bridging is the EVM-specific event that most often breaks a record. You send ETH to a bridge contract on Ethereum; some minutes later ETH appears at the same address on Arbitrum. Imported on one network only, that is ETH disappearing or ETH materialising. Imported on both, it is a transfer.

Whether a bridge is ever a disposal depends on what comes out the other end. The official rollup bridges give you the same asset on the other network, and most readings treat that as a transfer between your own wallets. Third-party bridges that hand you a wrapped or bridged token — a different contract, sometimes a different name — are harder, and the cautious reading is that you exchanged one asset for another. Either way, import both networks first; the question cannot even be asked until the two halves are in the same record.

Airdrops

EVM chains are where most of the large airdrops have happened — ARB on Arbitrum, the Blast and Berachain distributions, Linea's token, and countless protocol tokens. The general position is that an airdrop is income at its value when received, and that value becomes the token's cost basis. The IRS treats it as ordinary income. HMRC distinguishes an airdrop received for doing something — using a protocol, completing tasks — which is income, from one received for nothing at all, outside any trade, which is not income on receipt but is still a disposal when sold.

Most airdrops that are worth anything were earned by activity, so expect them to be income in most readings. The exception is the token that had no market when it landed; with no price, there is no value to recognise, and the cost basis is zero.

Spam, Dust and Review

Anyone can send anything to any EVM address, and an address with real activity attracts junk: tokens named after websites, fake versions of real tokens, NFTs that exist to make you visit a site. None of it is income, and a token with no market is worth nothing when it arrives.

CryptoTaxBridge does not filter spam automatically, because automated detection deletes real transactions often enough to be dangerous — the person who knows whether an obscure token was a genuine airdrop or a phishing lure is you. Every imported transaction can be reviewed, deleted and restored. How to find missing transactions covers the opposite problem, when something you expect is not there.

Wallets Are Labels, Not Sources

MetaMask, Rabby, Ledger, Trust Wallet, Rainbow, Zerion — on an EVM chain they are all the same thing: software holding a key to an address. The history belongs to the address and the network, not to the wallet. Switching wallets does not create a new history; using the same address in two wallets does not create two. MetaMask, Rabby and Ledger each have their own guide for the parts that differ, which are mostly about where the non-EVM chains live.

An EVM Import Checklist

Before generating a report, confirm:

the address is imported on every network it has activity on, not only Ethereum;
every address you controlled is included;
swaps appear as exchanges of one asset for another, with gas attached;
bridges have both networks imported, so the transfer matches;
staking, liquidity and protocol rewards appear as income with dates;
airdrops appear as income where a price existed at receipt;
the exchanges you funded the address from are connected;
spam tokens have been reviewed and removed.

Conclusion

The EVM family is one set of rules and many ledgers. Learn the rules once — swaps are disposals, rewards are income, gas is a cost, transfers need both sides — and apply them to every network the address touched. The reports that go wrong are almost never wrong about the rules. They are missing a chain.

Connect your wallets

Official Resources

This article provides general information and is not tax advice. Wallet software changes; where this article and your wallet's own documentation disagree, the wallet is right.