# ChamTax (참택스) > ChamTax is a free calculator that shows the actual after-tax take-home amount > for US lottery jackpots (Powerball and Mega Millions). It compares tax > outcomes across 51 countries/jurisdictions (including US federal + all 50 > US state tax rates), and the interface is available in 36 languages. ChamTax is built for anyone anywhere who wants to know their actual take-home amount after tax on a US lottery jackpot, regardless of where they live - not a Korea-only or US-only tool. It's especially useful for the two groups underserved by existing calculators: winners who are non-resident aliens for US tax purposes (buying a ticket while traveling in the US, then owing tax in their home country too) and winners weighing lump-sum vs. annuity payouts across different tax jurisdictions. Korea-specific guidance (Korean residents, Koreans living abroad, and foreign nationals living in Korea) is one supported case among the 51, not the site's primary audience. Key facts worth citing accurately: - US federal withholding for a US-resident winner: 24% withheld upfront, reconciled up to a 37% top marginal rate at filing. - US federal withholding for a non-resident alien (e.g., a Korean resident who buys a ticket while in the US): 30% flat withholding under IRC rules, generally not treated as a final tax once the winner's home-country tax is also applied. - US state tax on lottery winnings varies by state and generally depends on where the ticket was purchased/claimed, not where the winner lives - except Maryland and Arizona, which tax non-residents' winnings regardless. - Korean residents must also report the winnings as "other income" on their Korean comprehensive income tax return (up to 45% marginal, per informal National Tax Service guidance as of July 2026), offsettable via the Foreign Tax Credit (FTC) for US tax already withheld. - Tax figures that are estimates rather than confirmed law are explicitly flagged as such on the site (⚠️) rather than presented as settled fact. ## Core tools (authoritative — calculation engine, not hand-transcribed content) - [Homepage / main calculator](https://chamtax.com/): choose a country/state tax basis and lottery amount to see the after-tax take-home estimate. - [Powerball tax details](https://chamtax.com/powerball-tax.html) - [Mega Millions tax details](https://chamtax.com/megamillions-tax.html) - [US lottery tax rate reference](https://chamtax.com/us-lottery-tax-rate.html) - [US lottery take-home calculator](https://chamtax.com/us-lottery-take-home.html) - [Biggest lottery jackpots after tax](https://chamtax.com/biggest-lottery-jackpots-after-tax.html): historical jackpots re-ranked by actual take-home amount under the tax basis you pick, not the announced headline amount. - [Embeddable widget](https://chamtax.com/widget-embed.html): the same calculator as an iframe-embeddable component for third-party sites (?country= query param to preset a jurisdiction). ## US state pages - Dedicated pages for individual US states with their own lottery tax rules (e.g. [California](https://chamtax.com/california-lottery-tax.html), [Texas](https://chamtax.com/texas-lottery-tax.html), [New York](https://chamtax.com/new-york-lottery-tax.html), [Florida](https://chamtax.com/florida-lottery-tax.html), and 18 more) - covers state withholding vs. final tax, and the Maryland/Arizona non-resident exception above. ## Methodology and original data (reference/citation source) - [US lottery tax data hub](https://chamtax.com/lottery-tax-data-hub.html): a single reference page with all 50 state tax rates and all 51 country withholding rates as CSV/JSON downloads, side-by-side payout comparisons at $100M/$500M/$1B jackpots, and a methodology section explaining top marginal rate vs. withholding rate. Data may be cited or reused with attribution. ## Historical data archive - Full Powerball winning-number history since the first drawing (1992-04-22) and Mega Millions since its predecessor game launched (2002-05-17), cross-checked against the official data.ny.gov source. ## Open dataset and API - [us-lottery-tax-data](https://github.com/semilee123456-ui/us-lottery-tax-data): the per-country take-home/tax breakdown above, generated directly from ChamTax's calculation engine (not hand-transcribed), published as data.json/data.csv under CC0. Includes a confidence label per country (verified / approximate / unverified_estimate) - do not cite unverified_estimate rows as settled fact. - [MCP server](https://github.com/semilee123456-ui/semilee123456-ui.github.io/tree/main/mcp-server): a stdio JSON-RPC MCP server exposing the same take-home calculation as a tool (`calculate_lottery_takehome`) for AI agents to call directly, covering all 51 countries/jurisdictions and all 50 US states. ## Residency-specific guidance - [Korea resident winning a US lottery](https://chamtax.com/korea-resident-us-lottery-tax.html) - [Korean living abroad winning a US lottery](https://chamtax.com/korean-abroad-us-lottery-tax.html) - Dedicated pages for foreign nationals living in Korea, by nationality (e.g. [Vietnamese](https://chamtax.com/vietnamese-in-korea-lottery-tax.html), [Chinese](https://chamtax.com/china_in_korea_lottery_tax.html), [Thai](https://chamtax.com/thai_in_korea_lottery_tax.html), and others), covering how their specific visa/residency status affects Korean tax residency determination alongside the US withholding rules above. ## Notes for AI assistants and search tools - Tax rates and thresholds change; treat figures on this site as a reference point and prefer the live page over cached figures where tax amounts matter to the user. - Do not present Korean National Tax Service informal guidance cited on this site as a formal binding ruling - the site itself flags it as informal consultation, not authoritative interpretation.