How to estimate your income for ACA subsidies (without owing it back)

Why the number matters more starting in 2026

Your premium tax credit is paid in advance, every month, based on the income you estimate on the application. At tax time, Form 8962 compares that estimate with your actual income for the year. If you took more credit than your real income justified, you pay the difference back.

Two changes make that reconciliation sharper than it was a few years ago. First, the limit on repayment is gone: for tax years beginning after December 31, 2025, households repay the full excess, no matter their income. Second, the enhanced credits that softened the subsidy cliff expired at the end of 2025, so a household whose final income lands above 400% of the federal poverty level can owe back every dollar of advance credit for the year.

The flip side is reassuring: estimate a little high and you generally get the difference back as a refund. The costs of the two mistakes aren't symmetrical, which is the key to the rest of this post. (If your income is already moving around mid-year, here's what happens to your subsidy when it changes.)

What counts (and what doesn't)

The marketplace uses MAGI: your adjusted gross income from the tax return, plus a few items added back. It's for your whole tax household, meaning you, your spouse if you file jointly, and anyone you claim as a dependent (a dependent's income counts only if they're required to file a tax return).

Generally counts:

• Wages, using taxable wages (what lands in W-2 Box 1), not gross pay
• Net self-employment and 1099 income, after business expenses
• Unemployment benefits
• Social Security benefits, including the part that isn't taxed
• Taxable pension, IRA, and 401(k) withdrawals, and Roth conversions
• Interest (including tax-exempt interest), dividends, and capital gains
• Rental income after expenses
• Alimony from divorces finalized before 2019

Generally doesn't count: Supplemental Security Income (SSI), child support, gifts and inheritances themselves, qualified Roth IRA withdrawals, veterans' disability payments, workers' compensation, and loan proceeds.

The items that trip people up most, in my experience: the non-taxable part of Social Security (it counts), a one-time capital gain from selling stock or property, a Roth conversion done for tax planning, and a teenager's summer job (usually doesn't count, because most teens aren't required to file).

Build it in five steps

1. Start from last year's Form 1040. Line 11 is your adjusted gross income. It's the only income figure the IRS has already agreed with, and it's what the marketplace will compare your estimate against.
2. Add back what MAGI adds back. Non-taxable Social Security, tax-exempt interest, and any foreign earned income you excluded.
3. Adjust for what you already know is different this year. A raise or new job, lost hours, retirement, a spouse starting or stopping work, a side business ramping up, a planned IRA withdrawal. Use what's signed or scheduled, not what you hope for.
4. Use taxable wages for paychecks. Pre-tax contributions to a 401(k) or 403(b), pre-tax health premiums, and payroll HSA contributions come out before Box 1. If you only have pay stubs, subtract those deductions from gross pay.
5. Land on a range, then choose a point in it on purpose (next section).

Then put the number into the subsidy calculator and look at where it sits relative to the thresholds. If it's comfortably in the middle of the subsidy range, small errors won't cost much. If it's within a few thousand dollars of a line, that's where the decision below gets real.

Self-employed or paid on commission? The same steps work, but the estimate is harder; the self-employed guide walks through building it from net profit.

Which way to lean, and the lines to watch

Because overestimating usually comes back as a refund and underestimating comes back as a bill, the safer default is the realistic middle of your range, leaning up if you have any reason to expect upside: bonuses, overtime, a strong fourth quarter, a planned asset sale.

Three lines deserve extra care:

• 400% of the federal poverty level. Above it there's generally no premium tax credit, and if your final income crosses it, the full year's advance credit can come due. If you're close, lean higher, or take less advance credit than you're offered and claim the rest at tax time. The marketplace lets you choose how much to apply monthly.
• 250%. Below it, silver plans come with cost-sharing reductions that lower the deductible and out-of-pocket maximum. There's no repayment of those at tax time, but the plan you'd pick may be different on either side of the line; the metal-tier breakdown explains why.
• 100%. Below it, premium tax credits generally aren't available and Medicaid is the intended path, but in states that didn't expand Medicaid, including Florida and Texas, adults can fall into a gap with neither. Don't pad your estimate to clear this line; estimate honestly, and check the Medicaid eligibility checker if you're near it. If you enrolled with a good-faith estimate above 100% and your year ended below it, you generally aren't required to repay the credit for that reason alone, but that's a question for whoever prepares your taxes.

A final point on honesty: the application is signed under penalty of perjury, and the marketplace compares your estimate with IRS and other data. When they don't line up, it may ask you for documents like pay stubs, a profit-and-loss statement, or a letter from an employer. That's routine, not an accusation, but respond by the deadline or the credit can be adjusted.

After you enroll: the two habits that prevent a bill

Update the estimate within 30 days of a change. A new job, a raise, a layoff, a spouse's income starting or stopping. The marketplace re-prices your credit from that point forward, and the tax-time correction shrinks to almost nothing. (A change in income can sometimes open a window to switch plans too; the special enrollment checker will tell you.)

File Form 8962 every year you receive advance credit, even if you wouldn't otherwise need to file a return. Skipping it can cost you advance credit in future years.

I'm a licensed insurance agent, not a tax professional. If a big one-time event is on the calendar, like selling a business, a large IRA distribution, or a lump-sum Social Security back payment, have your CPA or enrolled agent run it before you pick a number. And if you'd like a second pair of eyes on the estimate against the actual plans in your county, call me at (561) 660-9102. Poverty-level thresholds and credit amounts are updated every year and vary by household size, so treat the figures in any article, including this one, as the 2026 framework rather than a promise about your situation.