ACA Subsidy Cliff

The ACA subsidy cliff describes what happens to the premium tax credit when a household's income rises above 400% of the federal poverty line. The credit, which subsidizes premiums for coverage bought through the Affordable Care Act Marketplace, is calculated on a sliding scale up to that ceiling and then stops entirely, so a small increase in income can cost a household thousands of dollars in lost subsidy. The word "cliff" is informal shorthand; the law simply sets eligibility at 100% to 400% of the poverty line, and the sharp edge at the top is the consequence. This page is about that edge. How the credit itself is computed is a separate topic.

The eligibility band for the premium tax credit runs from 100% to 400% of the federal poverty line under Internal Revenue Code section 36B. Within the band the credit shrinks gradually as income rises, because the household is expected to contribute a growing percentage of income toward a benchmark plan. At the top of the band the credit does not taper to zero; it ends. A household at 401% of the poverty line receives nothing, which for an older couple buying their own coverage can mean paying the full unsubsidized premium, often a large sum.

Two independent changes both took effect for 2026, and they are easy to conflate. First, the cliff itself returned. A temporary rule in effect for 2021 through 2025 had suspended the 400% ceiling and capped premiums at 8.5% of income at every level; that rule, titled a temporary rule for those years, expired at the end of 2025 and was not extended. Every model or article written during those years will say the cliff is gone; it is not. Second, and by a different legal mechanism, a 2025 law repealed the limits on repaying excess advance credits. Previously a household that underestimated its income and took too much credit in advance owed the excess back only up to a capped amount; now the full excess must be repaid at every income level. Reviving the enhanced credits would restore the sliding scale but would not by itself bring back the repayment caps, because they were removed by separate legislation.

One technical point drives the exact income figure and is worth stating carefully. The premium tax credit is computed against the prior year's federal poverty guidelines, so a credit for one coverage year runs on the poverty table published the year before. That is why the dollar income that marks 400% of the poverty line is not simply the current year's figure. The percentage, 400%, is the durable fact; the dollar amount depends on household size and which year's guidelines apply.

The practical consequence for planning is that near the cliff, income control matters enormously. A Roth conversion, a realized capital gain, or a year-end bonus that nudges income over 400% can trigger the loss of the entire credit and, because the repayment caps are gone, a full clawback of advance credits already received. Because it is a cliff and not a slope, a single dollar can be decisive.

Each year, a Marketplace enrollee estimates household income to determine the advance premium tax credit paid to the insurer, then reconciles it on the tax return. As estimated income approaches 400% of the poverty line, the credit shrinks; if actual income lands above the line, the credit for the year is zero, and any advance credit received must be repaid.

A hypothetical example of the edge. Suppose a 60-year-old couple's benchmark Marketplace plan costs $2,000 a month, and at an income just under 400% of the poverty line they qualify for a credit that covers most of it. If a late-year capital gain pushes their income to just over 400%, their credit for the year falls to zero. They now owe the full unsubsidized premium, and because the repayment caps were repealed, they must also pay back the entire advance credit they received during the year. A few thousand dollars of extra income can cost far more than that in lost and repaid subsidy. These figures are hypothetical.

Why the structure matters to plan around

• Knowing the cliff is live again makes income management near the ceiling a concrete, high-value planning task rather than an afterthought.
• The 400% line is a bright, checkable threshold, so it is possible to model whether a given decision crosses it.

The hazards

• The loss is all-or-nothing, so a single dollar over the line can erase the entire credit.
• Because the repayment caps were repealed, underestimating income no longer has a capped downside; the full advance credit is clawed back.
• Sources written in 2021 through 2025 describe a suspended cliff that no longer reflects current law.
• The exact income line depends on the prior year's poverty guidelines and household size, so it is not a single memorable number.