Updated August 3, 2026. Quick answer: with the cliff back in 2026, MAGI management stops being a tuning exercise and becomes a threshold problem. Below 400% of the poverty line every extra dollar costs you a few cents of subsidy. Cross it and you lose the whole credit at once. So the question is not “how do I lower MAGI” but “where exactly is my line, and what would push me over it”.
Find the line first
400% of the poverty line depends on household size and whether you are in Alaska, Hawaii or everywhere else. It is a specific dollar figure for you, not a general one — the calculator prints it. Everything below only matters relative to that number.
What actually moves ACA MAGI
- Retirement account withdrawals from pre-tax accounts — usually the largest controllable item.
- Realised capital gains, including a fund’s distributions you did not choose.
- Interest and dividends, including tax-exempt interest, which counts here even though it escapes ordinary tax.
- Social Security — and note it is the full benefit, not the taxable portion.
- Part-time work, which can quietly push a carefully planned year over.
What reduces it: HSA contributions, deductible retirement contributions if you still have earned income, and simply not realising income you have discretion over this year.
The mistake that costs the most
Treating this like ordinary tax planning, where being slightly over a line costs slightly more. Here it does not. A household $500 over the cliff loses the entire credit, which for an older couple can be many thousands of dollars — so the last few thousand of MAGI before the line is the most expensive income in the whole plan.
The corollary is that a small deliberate reduction can be worth an enormous amount, which is rarely true anywhere else in tax.
Which MAGI, though
There are several definitions and they do not agree. The ACA one includes tax-exempt interest and the full Social Security benefit; the IRMAA one is a different calculation on a different timetable — the three, side by side. Planning against the wrong one is a common and expensive error.
Roth conversions are their own decision
A conversion is voluntary MAGI, which makes it the sharpest instrument here and the easiest to misuse — converting into the cliff can cost more than the conversion saves. That trade-off has its own page: Roth conversions and the ACA subsidy, which covers the sequencing.
Related: what changed for 2026 · COBRA vs the marketplace.
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Percentages are from IRS Rev. Proc. 2025-25 (the 2026 applicable percentage table); poverty guidelines from 90 FR 5917, which is the schedule used for 2026 coverage; statutory rules from 26 U.S.C. 36B and 29 U.S.C. 1162 and 1165, all read at source on August 3, 2026. This is an estimate of the benchmark calculation, not a quote, and it is not tax advice. If Congress restores the enhanced credits this page changes — check the date above.