How Are Kalshi and Polymarket Combos Taxed? Parlays, Legs and Your Records

A combo is generally taxed as one position, not one per leg. On Kalshi each combo is its own market that pays a single amount, so you have one cost, one payout and one gain or loss. Polymarket combos are more complicated, because positions can be broken apart and part of the collateral returned. No IRS guidance addresses either, and a parlay-style contract is the type most likely to look like a wager.

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 combos work

Kalshi. Its Combos help page describes each combo as its own market, paying the product of its component values. Combos generally aren't voided. If a component can't resolve normally, for instance a player who doesn't enter the game, it settles under the underlying market's rules, generally at a last fair price set by the Exchange, so a combo can pay something other than $0 or $1. Combo settlement can take longer, because a separate review follows the individual events.

Polymarket. Its combos documentation shows combos tying together several markets. Collateral may stay locked until every underlying market resolves. "Collateral return" finds offsetting positions, decomposes them, merges complementary exposure back into pUSD, and leaves the remainder in residual positions.

Tax result on Kalshi

One combo, one row.

Under capital treatment, it's a short-term gain, in the year it settles. A losing combo is a $12 loss. Your Kalshi P&L statement should reflect this, since it's a single market.

A settlement at a fair price between $0 and $1 is treated like any other settlement: payout minus cost.

Timing

Settlement is what matters, under capital, other-income or gambling treatment. A New Year's Eve combo may not clear review until January. So a combo's last leg can finish in December, while the settlement falls in the new year. Note the dates, and use one consistent rule. See open positions at year end.

Are combos more likely to be gambling?

Probably, yes, though nobody has ruled on it. Arguments that event contracts aren't wagers rely partly on market structure: tradable positions, order books, regulated exchanges. A combo on several sports results is close to a parlay at a sportsbook. CFTC's 2026 swap proposal would treat event contracts as swaps while saying casino-style wagers aren't. Yet the CFTC itself says that doesn't determine tax.

Some advisers divide contracts by nature. That split needs a consistent rationale. See gambling vs capital gains for event contracts. If you mix treatments, a combo is the category where a gambling label is easiest to defend.

Gambling treatment and combos

Combos fit a per-market session well, since each is one market with one result. But they make gross figures large. Picture 500 small combos in a year:

At 24%, that's $648 of tax on $1,000 of profit, even with itemizing. Without itemizing, the whole $18,000 is taxed, for $4,320. Combo volume is expensive under this treatment. See the 90% limit.

Tax result on Polymarket

The simple case is a position bought and held to resolution: cost in, payout out.

The complicated case is collateral return. The docs describe Y(A) and N(A) being merged into pUSD with residual positions remaining. It helps to think of it in pieces:

1. Part of your position turns into pUSD. That's like a merge: a partial disposal.
2. The rest becomes a new residual position.
3. Your basis has to be divided between the two.

There's no rule on how to do this. The approach in split, merge and convert carries over: allocate basis by relative value at the time. The alternative of treating the whole thing as continuing until final resolution is simpler, but it's harder to support if you've received collateral back.

Example: you paid $400 for a combo position. Collateral return gives you $250 of pUSD and leaves a residual position worth $230. Total value is $480. Allocating by value, the $250 portion carries about $208 of basis ($400 × 250/480), for a $42 gain now, and the residual has about $192 of basis.

A wallet with many of these won't reconcile without careful data, and tools that only read trades may miss them. If your numbers look wrong, check for these events.

Do I need one row per leg?

For a Kalshi combo, no: it's a single market. For Polymarket, you report the positions you actually held and disposed of, which can include residual positions that have their own results.

Records

• The combo's ticker or market identifier
• Its legs, for gambling-versus-capital reasoning
• Purchase, settlement and fee data
• Any fair-price settlements
• Collateral return events and residual positions on Polymarket

Run the free OddsFile check: paste a Polymarket or Hyperliquid address and see your 2026 P&L under each treatment, no signup. Compare the check's cash result with your own deposits and withdrawals if you've used collateral return.

FAQ

Is a parlay on Kalshi gambling for tax purposes?

The IRS hasn't said. It's closer to a wager than a CPI contract, but no rule draws that line.

Does each leg count as a separate win or loss?

On Kalshi, each combo is one market with one payout, so one result is the natural reading.

Are combo winnings reported on a W-2G?

Kalshi's tax page doesn't list a W-2G.

What if a leg is voided?

Kalshi says the leg settles under the underlying market's rules, generally at a fair price, so the combo's payout changes rather than being refunded.