COS Elite Kalshi tax calculator: what it does, what it costs, where it stops

What it does

Inputs: filing status (single, married filing jointly, married filing separately, head of household), taxable income before Kalshi activity, total Kalshi winnings, total Kalshi losses, and whether you itemize.

It returns four estimates. Ordinary income: net profit as other income on Schedule 1, Line 8z. Short-term capital: each position on Form 8949 flowing to Schedule D. Gambling, itemizing: full winnings taxed with losses on Schedule A subject to a 90% cap. Section 1256 hypothetical: 60% of net gain at an assumed 15% long-term rate and 40% at your ordinary rate.

The itemize toggle changes only the gambling column, because that is the one treatment where losses are deductible solely on Schedule A.

• Tax year 2026; last updated July 9, 2026
• Built by Garrett Taylor, CPA #133092; reviewed by Leanne Grant, EA #00167954-EA
• Excludes state tax, self-employment tax, net investment income tax, credits and phaseouts

Pricing

Free. The page labels it a free tool and carries the disclaimer that it is not tax advice and that you should consult a licensed CPA before filing.

Venues and data

Kalshi only. The inputs are your own totals; nothing is imported from Kalshi.

Where it falls short

No state tax, which for a California or New York trader is a large share of the bill. TraderTax's calculator covers state; this one does not.

The Section 1256 column assumes a flat 15% long-term rate rather than deriving it from your income, so it is labeled a hypothetical.

Polymarket and other venues are out of scope. A trader on two venues has to sum by hand and lose the per-venue reporting differences.

Who should use it

A Kalshi-only trader who wants a credentialed federal estimate across all four treatments in under a minute, then takes it to a preparer for the state side.