What Is Modified AGI on Form 8962 and How to Calculate It?

Modified AGI on Form 8962 is your adjusted gross income plus three otherwise non-taxable income streams: tax-exempt interest, the nontaxable portion of Social Security benefits, and foreign earned income or housing amounts excluded under Section 911. You calculate it on Worksheet 1-1 in the Form 8962 instructions and enter the result on Line 2a. The IRS uses this figure, combined with any filing-required dependent’s MAGI on Line 2b, to measure household income for the Premium Tax Credit.¹

Why This MAGI Isn’t the AGI on Line 11

Your AGI on Form 1040, line 11 already includes wages, business income, capital gains, and above-the-line deductions. MAGI for the Premium Tax Credit starts from that number, then adds back income that Congress considers part of your ability to pay for coverage even though it escapes federal income tax. Someone with $80,000 of municipal bond interest has the same economic capacity as someone with $80,000 of wages; the add-backs close that gap.

One boundary matters before you start. This MAGI formula applies only to the Premium Tax Credit. The IRS uses different MAGI definitions for IRA contribution limits, the Net Investment Income Tax, and other purposes, and they don’t include the same add-backs. A MAGI figure you calculated for another form cannot be reused on Form 8962.²

The Three Add-Backs

The statute at 26 U.S.C. § 36B specifies exactly three items added to AGI.¹

Tax-Exempt Interest

Interest from municipal bonds and similar instruments appears on line 2a of Form 1040 but isn’t taxed. Every dollar of it counts for MAGI. Filers with sizable muni portfolios sometimes miss this because the income never touched their taxable income line.

Nontaxable Social Security Benefits

Line 6a of Form 1040 shows your total Social Security benefits; line 6b shows the taxable portion. Subtract 6b from 6a, and the difference is the nontaxable portion you must add back. If you received a lump-sum back payment covering earlier years, you can check the box on line 6c and elect to attribute part of the payment to the year it was earned, which may lower the nontaxable amount flowing into your current-year MAGI.³

Foreign Earned Income and Housing Exclusions

U.S. citizens and residents living abroad can exclude foreign earnings and housing costs on Form 2555.⁴ Those excluded amounts (Form 2555 lines 45 and 50) must be added back for MAGI. This mostly affects expats who buy Marketplace coverage during a year they return to the U.S.

Calculating MAGI Step by Step

Before you start, pull your completed Form 1040 and the Form 1095-A the Marketplace sent you. The 1095-A shows your monthly premiums and any advance credit payments already sent to your insurer.⁵ The MAGI worksheet itself is Worksheet 1-1 in the Form 8962 instructions.

Start with your AGI from Form 1040, line 11.
Add tax-exempt interest from Form 1040, line 2a.
Add the nontaxable portion of Social Security: line 6a minus line 6b.
Add any foreign earned income or housing amounts excluded on Form 2555 (lines 45 and 50).
Enter the total on Line 2a of Form 8962.

On a joint return, your spouse’s income is already inside the joint AGI, so the joint 1040 figures carry both of you into Line 2a automatically.⁶

Adding Dependent MAGI to Reach Household Income

Your MAGI is only part of the number Form 8962 actually uses. Household income combines your MAGI on Line 2a with the MAGI of every dependent who is required to file a return because their income exceeds the dependent filing threshold.¹ The combined dependent figure goes on Line 2b.

Filing thresholds change each year with inflation. For 2025, a single dependent under 65 had to file if gross income exceeded the greater of $1,350 or earned income plus $450. For 2026, the single-filer standard deduction rose to $16,100, and dependent thresholds typically adjust with it.⁷ Check the current-year filing requirements before deciding whether a dependent’s MAGI belongs on Line 2b.

A teenager with a summer job earning above the threshold has MAGI that flows into your household income. If you estimated lower income when you enrolled in Marketplace coverage, a dependent’s earnings can push you into a higher bracket and shrink your credit.

Why Precision Matters More in 2026

Two changes make an accurate MAGI figure especially important starting with tax year 2026.

First, the 400% federal poverty line cliff is back. From 2021 through 2025, the American Rescue Plan and the Inflation Reduction Act suspended the upper income cutoff for the Premium Tax Credit, so higher-income households could still receive a partial credit if their benchmark premium exceeded 8.5% of income. That provision expired on December 31, 2025.¹ For 2026, household income above 400% FPL means zero credit, no matter how expensive coverage is. For a family of four in the contiguous states, that ceiling is $132,000 (400% of the $33,000 poverty guideline).⁸ A few thousand dollars of missed tax-exempt interest can put you over.

Second, the repayment caps that limited excess advance credit payments are gone. Through 2025, filers below 400% FPL had capped repayments; a single filer between 200% and 300% FPL, for example, owed back no more than $975 regardless of how large the discrepancy was. Under Pub. L. 119-21, those caps no longer apply starting with tax year 2026. If your advance payments exceeded your actual credit by $3,000, you owe back the full $3,000. Underestimating income at enrollment now carries the full downside; if your circumstances change mid-year, updating your Marketplace account is the way to avoid a surprise at filing time.

Situations That Complicate the Calculation

Self-Employed Health Insurance Deduction

Self-employed filers who deduct Marketplace premiums on Schedule 1 hit a circular problem. The deduction reduces AGI, which reduces MAGI, which changes the credit, which changes the deductible premium, which changes AGI again. IRS Publication 974 gives two acceptable ways out: an iterative calculation that runs until the numbers stabilize, and a simplified method.⁹ Either works as long as the deduction plus the credit doesn’t exceed your total enrollment premiums. Estimating this by hand is where self-employed filers get into trouble; the Publication 974 worksheets are the safe path.

Married Filing Separately

If you were married at year-end, you generally must file jointly to claim the Premium Tax Credit at all. A married-filing-separately return usually disqualifies you.¹ Narrow exceptions exist for filers who lived apart from a spouse for the last six months of the year while maintaining a home for a dependent child, and for victims of domestic abuse who cannot safely file jointly. The Form 8962 instructions identify the specific boxes to check when either applies.

Lump-Sum Social Security Payments

A back payment covering prior years can be handled two ways. You can include the full amount in the current year, or you can elect on line 6c of Form 1040 to attribute the taxable portion to the earlier year it was earned. The election can lower the nontaxable Social Security add-back flowing into your current-year MAGI, which can keep you on the right side of an FPL threshold.³

Form 8962 must be attached to your Form 1040, 1040-SR, or 1040-NR, and if you received any advance payments during the year, filing the form isn’t optional even if you wouldn’t otherwise need to file.¹⁰ Most tax software builds the form from your 1095-A entries, but the MAGI figure it produces is only as accurate as the AGI, tax-exempt interest, Social Security, and Form 2555 amounts you’ve entered upstream.

1
Office of the Law Revision Counsel. 26 USC 36B – Refundable Credit for Coverage Under a Qualified Health Plan
2
Internal Revenue Service. Modified Adjusted Gross Income
3
Internal Revenue Service. Back Payments
4
Office of the Law Revision Counsel. 26 USC 911 – Citizens or Residents of the United States Living Abroad
5
Internal Revenue Service. Instructions for Form 8962 (2025)
6
Internal Revenue Service. 2025 Instructions for Form 8962 – Premium Tax Credit (PTC)
7
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
8
U.S. Department of Health and Human Services, Office of the Assistant Secretary for Planning and Evaluation. 2026 Poverty Guidelines – 48 Contiguous States
9
Internal Revenue Service. Publication 974 – Premium Tax Credit (PTC)
10
Internal Revenue Service. The Health Insurance Marketplace