Can Prediction Market Winnings Raise Your AGI and Hurt ACA Credits, Medicare or Social Security?

Yes. All three use a modified version of adjusted gross income, so trading profit raises each one. How much depends on your tax treatment. Capital, Section 1256 and other-income reporting generally raise AGI by the net result. Gambling treatment adds gross winnings to AGI, and losses come off later as an itemized deduction that never lowers AGI. A trader with $40,000 of winners and $38,000 of losers can add $2,000 under one treatment and $40,000 under another.

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 each treatment reaches AGI

The 2026 treatment isn't settled, so these are alternatives, and the choice has effects well beyond the income tax bracket.

ACA premium tax credits

The credit depends on household income relative to the poverty line, using AGI plus excluded foreign income, tax-exempt interest and untaxed Social Security, per §36B(d)(2)(B).

Two facts make 2026 harsher than recent years.

The cliff is back. The law removed the 400% ceiling only for 2021 through 2025. Under §36B(c)(1)(A), you must generally be between 100% and 400% of the poverty line. IRS FAQs state the same range. One dollar over means no credit. The 2025 poverty guideline for one person in the 48 contiguous states is $15,650, so 400% is $62,600. The 2025 Form 8962 instructions use the prior year's guidelines, so we expect the 2025 figure to apply to 2026 coverage. Confirm it in the 2026 instructions for your household.

Repayment has no cap. Before 2026, limits protected many households. The IRS says that for tax years after 2025, there's no repayment cap: if your credit is less than the advance payments, you repay the full difference with your return.

Example: a single enrollee expects $50,000 of income and receives $4,000 of advance credit during 2026. In October she wins on Kalshi. On capital treatment with a $14,000 net gain, her income is $64,000, above the $62,600 line, and all $4,000 is repaid. With a $10,000 gain, she stays under the line at $60,000, keeps the credit she's still due, and repays only any excess.

Under gambling treatment, her income would be measured with gross winnings. Wins of $14,000 alongside $13,000 of losses would still cross the line, on just $1,000 of profit.

If your income changes during the year, the IRS says to tell the Marketplace promptly so advance payments can be adjusted. Doing this in November limits what you repay in April.

Medicare IRMAA

Medicare Part B and Part D charge more at higher incomes. MAGI here is AGI plus tax-exempt interest, and it's usually taken from your return two years before the premium year. So 2026 income generally sets 2028 premiums.

The CMS figures for 2026 Part B, which use 2024 income, are:

These are brackets, not phase-ins. Crossing $109,000 by a dollar costs $81.20 a month, or $974 a year, per person, and Part D has its own surcharge. Figures for 2027 and 2028 weren't published as of this writing, so use these as a guide only.

One relief route doesn't help. Social Security lets you ask for a lower amount after certain life-changing events, but a POMS section lists capital gains, lottery winnings and casino winnings among examples that don't qualify. A one-off win is likely to stick.

Taxation of Social Security benefits

Here the test uses half of your benefits plus all other income, including tax-exempt interest. Publication 915 gives the base amount:

Above the base amount, part of your benefits becomes taxable, up to 85%. Each extra dollar of trading income can therefore raise taxable income by more than a dollar.

Example: Joan is single with $24,000 of benefits and $12,000 of pension income. Half her benefits plus pension is $24,000, so none of her benefits is taxable. A $10,000 net capital gain makes it $34,000, and part of her benefits becomes taxable. The Publication 915 worksheet gives the amount. Under gambling treatment, the figure would use gross winnings, which could push it much further.

What to do before year end

1. Measure both figures. Find your net result and gross winners. Run the free OddsFile check: paste a Polymarket or Hyperliquid address and see your 2026 P&L under each treatment, no signup.
2. Find your nearest line. $62,600 for one person on ACA coverage, or the Medicare bracket two years ahead.
3. Consider timing. Under capital treatment, realized losses on open positions before December 31 reduce net income.
4. Update the Marketplace if your income changed.
5. Check the treatment. Don't pick one for this effect alone, but do count it when you weigh them with a preparer.

FAQ

Do itemized gambling losses reduce MAGI?

No. They are below AGI, so all three tests ignore them.

Can I hold back winnings to stay under a line?

Realized income is what counts, so holding a position open generally defers it under capital treatment. Section 1256 marks open positions at year end, so that doesn't work there.

Does withdrawing to my bank count as income?

No. Income comes from the trades, not the transfer. See cashing out to your bank.