The two ACA subsidies in plain English
There are two distinct subsidies — most people only know about one. The Advance Premium Tax Credit (APTC) lowers your monthly premium. The Cost-Sharing Reduction (CSR) lowers your deductible, copays, and out-of-pocket maximum. Both come from the federal government, both flow through the marketplace, and both require enrolling on the exchange (off-exchange plans don't qualify).
APTC scales by income. CSR is binary by income band and only applies if you pick a Silver-tier plan. Picking Bronze or Gold instead can leave thousands of CSR dollars on the table for low-income enrollees.
APTC eligibility brackets (2026)
Eligibility runs from 100% of the Federal Poverty Level upward. Through 2025 the Inflation Reduction Act removed the old 400% FPL cliff and capped what anyone pays at 8.5% of household income for the benchmark Silver plan; whether that extension continues in 2026 depends on federal action. For most households, that means a real, sizable credit at almost every income level.
FPL is set by household size. For 2026 enrollment using 2025 FPL: 1 person = $15,650/yr, 2 = $21,150, 3 = $26,650, 4 = $32,150. The benchmark Silver plan in your county defines the credit amount; if you pick a cheaper plan, you keep the difference; if you pick a more expensive one, you pay the difference.
- 100–150% FPL — pay $0 for benchmark Silver
- 150–200% FPL — pay 0–2% of income
- 200–250% FPL — pay 2–4% of income
- 250–400% FPL — pay 4–8.5% of income
- 400%+ FPL — pay no more than 8.5% of income (through 2025 enhancement)
CSR — the second subsidy almost no one talks about
Cost-Sharing Reductions kick in at 100–250% FPL but ONLY on Silver-tier marketplace plans. They come in three tiers: CSR-94 (≤150% FPL), CSR-87 (150–200%), and CSR-73 (200–250%). The number is the effective actuarial value the plan provides after CSR.
Practical effect: a standard Silver plan might have a $5,500 deductible and $9,000 out-of-pocket max. With CSR-94, the same plan can have a $200 deductible and $2,800 OOP max — same network, same premium. CSR-87 lands somewhere in the middle. This is the single biggest reason for low-income shoppers to choose Silver over a cheaper Bronze plan.
Estimating your subsidy on the back of an envelope
First, project your 2026 modified adjusted gross income (MAGI). Use last year as a starting point and adjust for raises, job changes, or expected RSU vesting. Second, look up your county's benchmark Silver premium (varies $400–$900/mo for a 40-year-old non-smoker depending on county). Third, compare what you'd pay at your income bracket above against the benchmark.
The difference is your monthly APTC. Whether you take it monthly (lower premium) or claim it at tax time on Form 8962 is your choice. Most people take it monthly.
The income mistakes that cost real money
Under-projecting income: when actual income comes in higher than estimated, you owe back part of the credit at tax time (capped by income tier, but still painful). Over-projecting income: you leave subsidy dollars on the table monthly that you could have used to lower premiums all year.
Other common errors: forgetting to add self-employment income, forgetting that Social Security counts in MAGI, missing the 30-day window to update after a job change, and assuming a Bronze plan is cheaper than Silver after CSR (often false for households under 200% FPL).
Special Enrollment Periods (SEP)
If you're outside the November 1–January 15 Open Enrollment window, you can still enroll with a Qualifying Life Event: loss of coverage, marriage, divorce, birth/adoption, move to a new ZIP, citizenship change, or income change crossing a subsidy threshold (e.g., out of Medicaid eligibility). You have 60 days from the event to enroll. Some events also allow retroactive coverage; most don't.
Year-round SEP also exists for households under 150% FPL. If you qualify, you can enroll any month of the year.