How the credit is actually calculated
The mechanism surprises most people. The Marketplace works out what your household is expected to contribute toward coverage as a percentage of income, looks up the second-lowest-cost Silver plan in your county — the benchmark — and pays the difference as your credit.
That has two consequences. First, your credit is a fixed dollar amount, so applying it to a cheaper plan than the benchmark can drop your net premium sharply. Second, your credit depends on local pricing: identical households in different counties get different credits, because the benchmark plan costs different amounts.
What counts as income
The measure is modified adjusted gross income for the whole tax household, projected for the coverage year. It includes wages, net self-employment income, unemployment compensation, taxable interest and dividends, and certain untaxed items such as tax-exempt interest and non-taxable Social Security benefits.
It is projected, not historical. You are estimating the year ahead, and you are expected to update the estimate when circumstances change.
Cost-sharing reductions: the Silver-plan rule
Cost-sharing reductions are a second, separate subsidy that lowers your deductible, copays and out-of-pocket maximum. They are only available if you enroll in a Silver plan.
This produces the single most common expensive mistake in Marketplace shopping: a household eligible for cost-sharing reductions picks Bronze because the monthly premium is lower, and forfeits a Silver plan that would have had a far smaller deductible for a similar net cost. If you qualify, price the Silver plan properly before dismissing it.
| Subsidy | Reduces | Available on |
|---|---|---|
| Premium tax credit | Monthly premium | Any metal tier |
| Cost-sharing reduction | Deductible, copays, out-of-pocket maximum | Silver plans only |
Who is disqualified, and why
An offer of employer coverage that is considered affordable and meets minimum value generally makes you ineligible for a premium tax credit — whether or not you accept it. The affordability test now accounts for the cost of family coverage rather than employee-only coverage, which restored eligibility for some families previously caught by the so-called family glitch.
Eligibility for Medicaid or CHIP also routes you away from premium tax credits. Medicaid eligibility varies by state depending on whether the state expanded the programme, so the same income can lead to a different outcome across a state line.
Reconciliation at tax time
Advance credits are estimates. When you file, the Marketplace issues Form 1095-A and you reconcile the advance payments against what your actual income entitled you to on Form 8962.
If you earned less than projected, you receive the difference. If you earned more, you may repay part of the advance, subject to repayment caps for lower-income households. Nothing about this process is unusual — but it is why an accurate, updated projection is worth the five minutes it takes.
Special Enrollment Periods and mid-year changes
Outside Open Enrollment you need a qualifying life event to enroll or change plans — losing coverage, moving, marriage, birth or adoption, and certain income changes for people already enrolled. Most Special Enrollment Periods run 60 days from the event.
Report income and household changes as they happen rather than waiting. It adjusts your credit going forward and keeps reconciliation uneventful.
Checking your own eligibility
Because the calculation depends on your county's benchmark plan, no national estimate is reliable. Use the official Marketplace for your state, which applies your actual county filings.
Amy can tell you in 90 seconds which subsidy pathway is likely to apply to your household and what to check first, then hand you to a licensed broker for exact figures. We do not display premiums because the honest number can only come from your county's filed rates.
