QastLedger
It's common to end up with more than one Polymarket account: one set up with an email login, another with a browser wallet, maybe a third you tried once. For taxes, all of them count, and they have to be combined into one record.
Step 1: List every wallet you've used
Go through each login you've ever used with Polymarket and write down the wallet address for each account. Remember that the address to use is the one Polymarket shows on your profile, which may not be the same as your login wallet. Our guide on finding your Polymarket trade history explains the difference.
Include accounts you've stopped using. If you traded from them during the tax year, those trades still need to be reported.
Step 2: Pull the history for each one
Each wallet has its own separate trade history on the blockchain. Pull every one of them for the full year.
Step 3: Don't count transfers as trades
Moving USDC from one of your wallets to another isn't a trade, and it isn't a taxable event. It's like moving cash between your own bank accounts. Only buys, sells and market resolutions create gains or losses.
The same goes for deposits and withdrawals between Polymarket and an exchange you own an account at. Count the trading, not the money moving between your own accounts.
Step 4: Check for duplicates
If you've ever imported the same history twice, for example once from a CSV and once by connecting the wallet, the same trades can show up twice. Scan your combined list for positions that appear more than once before you total anything.
Step 5: Apply one treatment across all of them
Your tax treatment for Polymarket should be the same across all your wallets. The platform and the contracts are the same, so the answer shouldn't change based on which account you traded from. Read How to report Polymarket trades for the options.
This guide is general information, not tax advice. Tax treatment of event contracts is still evolving, so confirm how it applies to you with a tax professional.