How to Estimate Income for the ACA Premium Tax Credit Safe Harbor

To estimate your income for the ACA premium tax credit, project the modified adjusted gross income of everyone in your tax household for the coming calendar year, using pay stubs, prior-year returns, and realistic assumptions about raises, bonuses, and side income. The number you give the Marketplace should sit between 100% and 400% of the federal poverty level for your family size, and it should reflect a good-faith effort rather than a hopeful guess. Getting this estimate right matters more for 2026 than in any recent year: Congress removed the repayment caps that used to soften the blow when advance credits exceeded what you were actually entitled to, and the 400% income ceiling is back as a hard cliff.¹²

What Counts as Income for the Credit

The premium tax credit uses modified adjusted gross income, or MAGI, which is broader than the AGI line on your tax return. Start with adjusted gross income, then add back three categories people routinely miss.¹

Tax-exempt interest, including interest from municipal bonds you don’t pay federal tax on.
The portion of Social Security benefits that isn’t included in your gross income. Retirees with modest incomes often pay no tax on their Social Security, but the full benefit amount counts here.
Foreign earned income you excluded on your tax return if you worked abroad.

Then add every other household member. Household income is the combined MAGI of you, your spouse if you file jointly, and every dependent who was required to file a tax return for the year.¹ A college-aged dependent with a part-time job that triggers a filing requirement adds to household income. Forgetting a working spouse’s earnings or a dependent’s summer job is one of the most common reasons people owe back excess advance credits at tax time.

The 2026 Income Range You’re Aiming For

Eligibility runs from 100% to 400% of the federal poverty level. For 2026, the poverty level is $15,960 for a single person in the 48 contiguous states and $33,000 for a family of four.³ That puts the qualifying range at roughly $15,960 to $63,840 for a single filer and $33,000 to $132,000 for a family of four.⁴

The upper number is a cliff, not a slope. From 2021 through 2025, temporary legislation lifted the 400% cap so higher-income households could still receive partial credits. That expansion expired on January 1, 2026.² If your actual 2026 income exceeds 400% of the poverty level by a dollar, you lose the entire credit and must repay every advance payment you received during the year. That makes the top of the range the most important number to watch when you build your estimate, especially if a bonus, a second job, or an investment sale could push you over.

Estimating Variable and Self-Employment Income

If your income fluctuates, base your estimate on documented history rather than optimism. Look at last year’s tax return, year-to-date pay stubs, and any contracts or recurring clients you already have lined up. For self-employed income, the Marketplace uses your net earnings, meaning revenue minus business expenses, the same figure you’d report on Schedule C.⁵

A middle-of-the-range estimate is usually safer than either extreme. Overestimating shrinks your monthly advance payment and leaves subsidy money on the table each month, though you’ll recover it at tax time. Underestimating produces a larger advance now and a repayment obligation later, with no cap on the amount you owe back for 2026. If your income shifts as the year progresses, don’t wait until filing season to reconcile the difference on paper. Update the Marketplace instead.

If Your Income Falls Below the Poverty Level

The credit is designed for households earning at least 100% of the poverty level, which creates a trap: someone whose income drops below that floor mid-year, say from a job loss, would technically be disqualified and could be forced to repay everything.

Treasury Regulation 1.36B-2(b)(6) prevents that outcome. If you enrolled through the Marketplace, the exchange estimated your household income would fall between 100% and 400% of the poverty level, and advance payments were actually paid on your behalf, you remain eligible for the credit even if your year-end income turns out below 100%.⁶ The regulation treats your income as though it stayed in the qualifying range.

The catch is that your original estimate must have been made in good faith. The safe harbor vanishes if you gave the Marketplace an income number with intentional or reckless disregard for the facts. Reckless disregard means making little or no effort to verify your estimate when the circumstances would have prompted a reasonable person to check.⁶ Intentional disregard means you knew the number was wrong when you reported it.⁷

In practice, this standard is forgiving for people who genuinely tried. Basing your estimate on last year’s tax return, current pay stubs, or a realistic projection of freelance work is enough. You aren’t expected to predict the future perfectly, and the IRS bears the burden of proving reckless or intentional behavior during an examination.⁷ You’re also protected when you rely on guidance from Marketplace navigators, certified application counselors, agents, or brokers, provided you gave them accurate information about your situation. If your employer gave you incorrect information about available coverage, you aren’t held responsible for that error either.

Update the Marketplace When Things Change

An income estimate isn’t a one-and-done submission. The Marketplace expects updates whenever your household income or circumstances shift meaningfully. Changes that require reporting include a raise, a new job, a job loss, marriage, divorce, the birth of a child, a move, gaining or losing other health coverage, and changes to immigration or disability status.⁸

Federal guidance sets a deadline of 30 days after the change for income shifts and moves to a different state.⁹ Prompt reporting lets the Marketplace resize your advance payments to match reality. If your income rises, your monthly advance shrinks and you owe less at reconciliation. If your income drops, you may qualify for a larger advance right away. This is the single most effective habit for avoiding a large repayment surprise, and in 2026 it matters more than ever, because there is no cap to soften an overpayment.

What Happens If Your Estimate Was Off

At tax time, every person who received advance credit payments files Form 8962 to reconcile what the Marketplace paid to your insurer against the credit you actually earned based on final income and family size. You’ll need Form 1095-A from the Marketplace, which arrives by late January and lists monthly premiums and advance credit amounts.¹⁰¹¹

The math produces one of two outcomes. If you were entitled to more credit than you received, the difference reduces your tax bill or increases your refund. If your advance payments exceeded your actual credit, you owe the excess back.

For 2026, that excess repayment is unlimited. Federal legislation enacted in 2025 struck the repayment cap from the statute entirely, effective for tax years beginning after December 31, 2025.¹ Through 2025, a single filer under 200% of the poverty level who received too much advance credit owed back no more than $375 regardless of the actual overpayment. That protection is gone. Someone who estimated $30,000 in income but earned $45,000 could owe thousands of dollars back with no cap and no phase-out.¹² If you can’t pay the full amount when you file, the IRS offers installment agreements similar to those available for other tax debts.

The takeaway for building your estimate: check your projected household income against the 400% ceiling with a margin of safety, add back the MAGI items that don’t show up on your paycheck, include every filer in the household, and update the Marketplace the moment your situation changes. A conservative estimate you can defend as reasonable is worth more than an optimistic one that maximizes your monthly advance.

1
Office of the Law Revision Counsel. 26 USC 36B – Refundable Credit for Coverage Under a Qualified Health Plan
2
Congressional Research Service. Enhanced Premium Tax Credit and 2026 Exchange Premiums
3
U.S. Department of Health and Human Services. 2026 Poverty Guidelines
4
Internal Revenue Service. Eligibility for the Premium Tax Credit
5
HealthCare.gov. Reporting Self-Employment Income to the Marketplace
6
eCFR. 26 CFR 1.36B-2 – Eligibility for Premium Tax Credit
7
Federal Register. Premium Tax Credit Regulation VI
8
HealthCare.gov. Which Income and Household Changes to Report
9
Centers for Medicare and Medicaid Services. Reporting Life Changes – Types of Qualifying Life Events
10
Internal Revenue Service. Instructions for Form 1095-A
11
Internal Revenue Service. Reconciling Your Advance Payments of the Premium Tax Credit
12
Internal Revenue Service. Updates to Questions and Answers About the Premium Tax Credit