It's one of the most counterintuitive things that happens on the Health Insurance Marketplace: you take a person off your plan, you're now insuring fewer people, and your monthly bill goes up.

It isn't a glitch, and it usually isn't a mistake by the Marketplace. It's the arithmetic of how premium tax credits work. Once you see the formula, the whole thing makes sense.

The formula behind your subsidy

Your monthly premium tax credit isn't a percentage discount. It's a fixed dollar amount calculated like this:

Subsidy = Benchmark premium − Your required contribution

Two moving parts, and removing a household member can move both of them in the wrong direction.

The benchmark premium is the cost of the second-lowest-cost silver plan in your area for exactly the people you're covering. It's a reference price. It has nothing to do with the plan you actually chose — it's just the yardstick the government uses to size your credit.

Your required contribution It's your household income multiplied by an "applicable percentage." That percentage is set by where your income falls relative to the federal poverty level — and the FPL depends on how many people are in your tax household.

That last point is the one that trips people up. Your subsidy depends on two different headcounts: who's on the plan (which sets the benchmark) and who's in your tax household (which sets the poverty threshold). Removing someone can change one, the other, or both.

Two different kinds of "removing someone"

They come off the plan but stay in your tax household 

Think of an adult child who takes a job with employer coverage but is still your dependent, or a spouse who ages into Medicare while you still file jointly.

Your household size doesn't change, so your required contribution in dollars stays exactly the same. But the benchmark is now priced for fewer people, so it drops — and your subsidy drops right along with it, dollar for dollar.

Meanwhile, your actual premium only falls by whatever that person cost on your plan. If you're on a bronze plan that's cheaper than the benchmark silver, the benchmark falls by more than your premium does. Your net cost goes up.

They leave your tax household entirely

An adult child starts filing their own return. A divorce finalizes. A dependent you used to claim no longer qualifies.

Now both levers move against you. The benchmark drops (fewer people covered) and your poverty threshold drops (smaller household). If your income didn't fall by much when that person left — which is common when the departing person earned little — the same dollars of income now represent a much higher percentage of the poverty level. Higher FPL percentage means a higher applicable percentage, which means a bigger required contribution, which means an even smaller subsidy.

Fewer people, less coverage, bigger bill.

A worked example

Meet the Smith household in 2026: Maria (52), Sam (50), and their son Liam (23), whom they claim as a dependent. Household income is $68,000. They're enrolled in a bronze plan.

For 2026 coverage, the Marketplace uses the 2025 federal poverty guidelines: $26,650 for a household of three, $21,150 for two.

Before — three people on the plan, three in the tax household

Income as % of FPL                                                               $68,000 ÷ $26,650 = 255%

Applicable percentage                                                         8.59%

Required contribution                                                         $68,000 × 8.59% ÷ 12 = $487/mo

Benchmark silver for 3 ($840 + $800 + $450)                $2,090/mo

Subsidy ($2,090 − $487)                                                       $1,603/mo

Their bronze plan ($705 + $675 + $380)                           $1,760/mo

What they actually pay                                                  $157/mo

After — Liam turns 24, gets a job, and files his own return

Income as % of FPL                                                              $68,000 ÷ $21,150 = 322%

Applicable percentage                                                        9.96%

Required contribution                                                         $68,000 × 9.96% ÷ 12 = $564/mo

Benchmark silver for 2 ($840 + $800)                             $1,640/mo

Subsidy ($1,640 − $564)                                                        $1,076/mo

Their bronze plan ($705 + $675)                                        $1,380/mo

What they actually pay                                                  $304/mo

Their premium went down $380 a month. Their bill went up $147 a month — a 94% increase — for one less person.

Here's exactly where the money went:

• Benchmark fell by Liam's silver rate: −$450 of subsidy
• Required contribution rose because the household shrank: −$77 of subsidy
• Total subsidy lost: $527/mo
• Premium saved by dropping Laim from the bronze plan: +$380/mo
• Net change: +$147/mo

The subsidy was tied to what a silver plan would have cost for Liam. The savings were only what a bronze plan actually cost for him. That gap is the whole story.

And notice: even in the gentler version — where Liam stays a dependent and only leaves the plan — the household of three keeps its $487 contribution, the subsidy falls to $1,153, and the Smith's still pay $227/mo instead of $157. Up either way.

The 400% cliff makes this much worse in 2026

The enhanced premium tax credits from the American Rescue Plan and Inflation Reduction Act expired at the end of 2025, reverting the rules back to their pre-2021 version. Two consequences matter here.

The subsidy cliff is back. Eligibility now runs from 100% to 400% of the federal poverty level, and the 400% cliff returned January 1, 2026. Above 400%, the credit isn't reduced — it's zero.

Because the cliff is defined by household size, shrinking your household can shove you over it without your income changing at all. A family of four earning $125,000 sits at 389% of poverty and qualifies. Drop to a household of three and the 400% ceiling falls from $128,600 to $106,600. That same $125,000 is now 469% of poverty, and the entire subsidy disappears.

Repayment is unforgiving now. Beginning in plan year 2026, there is no limit on how much excess advance credit you must repay when you reconcile at tax time. The old caps of a few hundred to a few thousand dollars are gone. If you don't report a household change and keep collecting a credit you no longer qualify for, you'll owe every dollar of it back.

What to do about it

Report the change right away. Marketplaces generally want household changes reported within 30 days. 

Re-shop your plan, don't just remove the person. This is the step almost everyone skips. Your plan choice was optimized around an old subsidy. When the subsidy shrinks, the math that made bronze attractive can flip. If your credit is now smaller relative to the benchmark, a silver plan may cost less out of pocket than you'd expect, and it comes with better coverage. Run the numbers on the actual plans, not just your current one.

Update your income estimate at the same time. If the person who left was contributing income to your tax household, your projected income should come down too — and that partially offsets the smaller poverty threshold. Households often update the headcount and forget the income.

If it's a divorce, understand shared policy allocation. When one policy covered people who now file separate returns, you and your ex allocate the premiums, the benchmark, and the advance credit between your two returns. Agreeing on the percentages ahead of time avoids a mess in April.

The takeaway

A Marketplace subsidy isn't a discount on your plan. It's the gap between a benchmark price and what the law decides you can afford — and both of those numbers are calculated from your household. Change the household and you change the subsidy, sometimes by more than you change the premium.

Fewer people on the plan almost always means a lower premium. It does not always mean a lower bill.

This is general information, not tax or legal advice. Premiums, benchmark plans, and poverty guidelines vary by state, county, and age.