Is Funding Polymarket With ETH, BTC or SOL Taxable? Deposits Explained

Depositing stablecoins you already own into Polymarket isn't income, but funding your account with ETH, BTC, SOL or another volatile token usually is a taxable sale, because that token gets swapped along the way. You owe capital gains tax on any rise in value since you bought it, even if you then lose every bet. That gain exists no matter how you classify your Polymarket trades.

OddsFile is software, not tax advice. The IRS has not issued guidance on how prediction-market contracts are taxed. This article explains the options and the sources behind them; a tax professional can tell you which position fits your situation.

How a deposit becomes a sale

Polymarket's bridge documentation says you can send assets from Ethereum, Solana, Bitcoin, Tron and other EVM chains, and that "assets are bridged and swapped to pUSD automatically."

That automatic swap is the taxable moment. The IRS FAQ says that exchanging virtual currency for other property, including another virtual currency, produces a capital gain or loss. You didn't click "sell," but you gave up ETH and got something else.

Deposit types at a glance

Worked example

In February 2024 you bought 2 ETH for $5,000 ($2,500 each). In October 2026, you send 1 ETH to your Polymarket deposit address. It's worth $3,500 when swapped, and you receive about 3,490 pUSD after $10 of bridge and swap costs.

The prices in this example are illustrative. The gain is long-term because you held for more than a year, so long-term rates apply. Had you bought it nine months earlier, the same gain would be short-term and taxed at ordinary rates.

Now say you bet the whole 3,490 and lose. You still have a $990 capital gain on the ETH. Under capital treatment, your $3,490 Polymarket loss offsets it. Under gambling treatment, it doesn't: the loss goes against winnings on Schedule A, while the $990 stays on Schedule D. This trap can catch people who funded with appreciated crypto and treat the betting side as gambling. See gambling vs capital gains for event contracts.

Timing

The sale happens when the swap executes, not when you pick a market. The holding period of the outgoing token stops there, and the basis clock on pUSD starts. A deposit on December 30 that swaps on December 30 is a 2026 event even if you trade in January.

If the token is below your cost, the swap creates a capital loss. Under current law, wash sale rules apply to stock or securities, and the IRS treats digital assets as property, but that may change. See the wash sale rule and prediction markets.

Fees

Bridge, swap and gas fees generally aren't deductible as separate expenses. They change your numbers instead. The regulations include allocable transaction costs in digital asset basis. In practice, use the amount you actually received as your starting point and keep the fee in your records. Paying a network fee with a token is itself a small disposal of that token. H.R. 10357 would, as introduced, exempt fees of $10 or less from gain recognition from 2028, but it isn't law.

Which units did you sell?

If you bought ETH at several prices, the gain depends on which units moved. Since January 1, 2025, Treas. Reg. §1.1012-1(j) works wallet by wallet. In an unhosted wallet, the default is earliest acquired first, unless you identified specific units no later than the sale in your own records. See cost basis methods for what counts.

Will you get a form?

A swap through a non-custodial route may produce no 1099-DA at all, which doesn't change whether it's reportable. If a custodial exchange sells the token for you, that exchange may send a 1099-DA. Sending coins from an exchange to your own address is a transfer, not a sale, so it shouldn't appear as proceeds. If it does, the IRS says the transfer is still non-taxable.

Either way, answer the digital asset question Yes and put the swap on Form 8949.

How to do it better next time

• Sell first, deliberately. If you're going to fund with crypto, choose which lot you sell, ideally long-term, and do it on purpose.
• Fund with stablecoins or dollars if you have them. That usually avoids a gain altogether.
• Set aside tax. Your bankroll is smaller than it looks if the deposit created a gain.

For the whole picture, including how Polymarket activity itself is taxed, read Polymarket taxes: the complete guide.

Run the free OddsFile check: paste a Polymarket address and see your 2026 P&L under each treatment, no signup. Add any gains from funding swaps to what it shows, since those come from the crypto you sold rather than your trades.

FAQ

Is sending USDC to Polymarket taxable?

Sending your own USDC isn't income. Wrapping and bridging are unsettled, with near-zero dollar effects, and a crypto fee is a small disposal.

I deposited ETH but never traded. Do I owe tax?

If it was swapped, generally yes. The swap is the sale, whether or not you traded after it.

Can a Polymarket loss cancel the gain from my deposit?

Under capital treatment, generally yes. Under gambling treatment, no.

Do I need to report a swap under $600?

Yes. There is no minimum for reporting a capital gain. Thresholds control forms, not taxability.