Social Security income is where most ACA MAGI calculations go wrong at intake. Federal income tax applies to 50 to 85 percent of Social Security benefits depending on provisional income. ACA MAGI under IRC Section 36B applies to 100 percent of the gross benefit, including the portion that does not appear on the taxable income line of a federal return. A retired client with $24,000 in annual Social Security income may tell a broker they have $12,000 to $20,000 in SS income because that is the taxable portion on their 1040. For ACA subsidy purposes, all $24,000 counts.
Key Takeaways
- ACA MAGI is defined under IRC Section 36B as adjusted gross income plus three items: non-taxable Social Security benefits, tax-exempt interest, and foreign income excluded from US taxes. For a W-2 client with no Social Security income and no tax-exempt interest, MAGI is essentially AGI.
- The full gross Social Security benefit counts for ACA MAGI, including the non-taxable portion. Federal income tax taxes 50 to 85 percent of SS benefits based on provisional income thresholds. ACA subsidy math uses 100 percent. A client who tells a broker they have $14,000 in SS income may be citing the taxable portion of a $24,000 gross benefit.
- SSDI (Social Security Disability Insurance) counts toward ACA MAGI because it is an earned benefit funded by payroll taxes. SSI (Supplemental Security Income) does not count because it is need-based assistance. Brokers who confuse the two programs systematically over-count income for SSI recipients.
- Alimony received under divorce agreements executed before January 1, 2019 is taxable income and counts toward MAGI. Agreements finalized on or after that date follow the TCJA rule: alimony is not income to the recipient and not deductible by the payor. Asking the client when the agreement was finalized is a one-question fix.
- Tax-exempt interest from municipal bonds is added back to AGI for ACA MAGI purposes even though it does not appear as taxable income. A client with $8,000 in municipal bond interest has $8,000 added to their MAGI regardless of the federal tax treatment.
The three additions to AGI that define ACA MAGI
For most clients, ACA MAGI is close to AGI. The calculation diverges in three specific situations. Under , MAGI is AGI plus:
- Non-taxable Social Security benefits. The full gross SS benefit minus the portion already in taxable income.
- Tax-exempt interest income. Municipal bond interest that is excluded from federal taxation is added back for ACA purposes.
- Foreign earned income excluded under sections 911, 931, or 933. Income excluded from US taxation by treaty or exclusion is added back.
For a standard W-2 employee with no Social Security income, no municipal bonds, and no foreign income, ACA MAGI and AGI are the same number. The gap opens only when one of these three items applies. For self-employed clients, the MAGI calculation starts at a different AGI because net business profit replaces wages as the base income figure.
Income types: what counts and what does not
The comprehensive reference brokers use for intake. Sorted by how frequently each type appears in the ACA broker's client base.
| Income type | Counts for MAGI? | Note |
|---|---|---|
| Wages and salaries | Yes | After pre-tax deferrals to 401(k), 403(b), and similar plans. |
| Self-employment net income | Yes | Schedule C or F net profit after deductible business expenses. Not gross revenue. |
| Social Security benefits (full gross amount) | Yes | Including the non-taxable portion. The most common intake error. |
| Social Security Disability Insurance (SSDI) | Yes | Treated identically to retirement SS. Full gross benefit counts. |
| Traditional IRA and 401(k) distributions | Yes | Taxable portion only. Roth qualified distributions do not count. |
| Pension and annuity income | Yes | Taxable portion as reported on the 1099-R. |
| Capital gains (net) | Yes | Short- and long-term. A large investment sale in the plan year can shift MAGI substantially. |
| Net rental income | Yes | Gross rent minus deductible expenses. Passive loss rules apply. |
| Taxable interest and ordinary dividends | Yes | From bank accounts, CDs, taxable bonds, and equity holdings. |
| Tax-exempt interest (municipal bonds) | Yes | Added back to AGI for ACA purposes even though not taxable federally. |
| Unemployment compensation | Yes | Federally taxable and counted in full. |
| Alimony received (agreements before January 1, 2019) | Yes | Taxable under pre-TCJA law. Alimony from newer agreements does not count. |
| Foreign income excluded under Section 911 | Yes | Added back to AGI for ACA MAGI even though excluded from federal taxes. |
| Supplemental Security Income (SSI) | No | Need-based program, not taxable, not counted for MAGI. |
| Child support received | No | Not taxable, not counted regardless of amount. |
| Workers compensation | No | Not taxable federally, not counted. |
| VA disability compensation | No | Service-connected and non-service-connected payments are excluded. |
| Roth IRA qualified distributions | No | Not taxable after age 59.5 with a five-year-old account. Does not affect MAGI. |
| Home sale gain within the IRC 121 exclusion | No | $250,000 single / $500,000 married exclusion. Excluded gain never enters AGI. |
| TANF and public assistance | No | Not income for federal tax purposes, not counted. |
Reference as of plan year 2026. MAGI treatment reflects IRC Section 36B and applicable IRS guidance. Individual circumstances may vary.
SSDI versus SSI: the distinction most brokers skip
Both programs are administered by the Social Security Administration. They are not interchangeable for ACA purposes.
SSDI (Social Security Disability Insurance) is funded by payroll taxes paid during the recipient's working years. It is an earned benefit, it is taxable, and the full gross amount counts toward ACA MAGI under the same rule that applies to retirement Social Security.
SSI (Supplemental Security Income) is a needs-based payment for aged, blind, or disabled adults with limited income and resources. It is not funded by payroll taxes, it is not taxable, and it does not count toward ACA MAGI. A client who receives only SSI has zero income for ACA MAGI purposes from that source alone, which may put them below the Medicaid threshold in expansion states.
Some clients receive both: a small SSDI benefit and an SSI supplement to bring their total income to the SSI floor. In that case, the SSDI portion counts toward MAGI and the SSI supplement does not. The 1099-SSA or SSA benefit letter can clarify the split.
The TCJA alimony rule change that still trips up brokers
The Tax Cuts and Jobs Act of 2017 changed the federal tax treatment of alimony effective January 1, 2019. For divorce and separation agreements executed on or after that date, alimony is no longer income to the recipient and no longer deductible by the payor. The change applies to the agreement execution date, not the divorce proceedings start date.
For ACA purposes: alimony from a pre-2019 agreement counts toward the recipient's MAGI because it is taxable income. Alimony from a post-2018 agreement does not count. A broker who does not ask when the agreement was finalized will either include income that should not be there or miss income that should be.
The question at intake: “When was your divorce or separation agreement signed?” If before January 1, 2019, include the full alimony amount. If after, it does not count.
Municipal bond interest and the tax-exempt trap
Clients with municipal bond portfolios are accustomed to their interest income not appearing as taxable income on their federal return. For ACA MAGI, it is added back. A retired client who holds $200,000 in municipal bonds yielding 4 percent generates $8,000 in interest that, for ACA purposes, increases their MAGI by $8,000 even though that income is federally tax-exempt.
The same logic applies to state and local bonds, Puerto Rico bonds, and any other interest excluded from federal gross income under the tax-exempt interest rules. The client may not volunteer this information because they do not pay tax on it and may not think of it as income. The broker who asks specifically about tax-exempt interest at intake is the one who avoids the February reconciliation call.
Clients who use Quotit or any other quoting tool that shows subsidy estimates based on income inputs will get an estimate that is only as accurate as the MAGI figure entered. The tool has no way to validate whether income was correctly categorized. The intake conversation is where accuracy is set or missed.
The intake questions that catch MAGI errors
Most MAGI errors come from four sources: the Social Security non-taxable portion, tax-exempt interest, incorrect alimony treatment, and self-employment clients using gross revenue instead of net profit. The what-is-MAGI-for-ACA reference covers the self-employment calculation in detail. For the others, these intake questions close the gap:
- “What is your gross monthly Social Security benefit before any deductions?” Not the taxable portion. The gross.
- “Do you receive disability payments from Social Security? Is it SSDI or SSI?” Two different answers.
- “Do you receive any tax-exempt interest, such as from municipal bonds?” Clients with bond portfolios often do not volunteer this.
- “Do you receive alimony? When was your divorce agreement signed?”
- “Do you take distributions from any retirement accounts? Are they traditional or Roth?”
Five questions. Combined with the self-employed income check, they cover the vast majority of MAGI calculation errors before they reach . Use the ACA subsidy calculator to test the MAGI figure against current APTC thresholds before the quote call.
FAQ
Questions brokers encounter when working through MAGI income types with clients.
Does Social Security income count toward ACA subsidy calculations?
Yes, and the full gross Social Security benefit counts, not just the taxable portion. Federal income tax applies to 50 to 85 percent of Social Security benefits based on provisional income levels. ACA MAGI under IRC Section 36B adds back the non-taxable portion to adjusted gross income, so all of it counts. A retired client with $28,000 in annual Social Security benefits has $28,000 included in their ACA MAGI regardless of how much of that is taxable on their federal return.
Does alimony count as income for ACA purposes?
It depends on when the divorce or separation agreement was executed. Under agreements finalized before January 1, 2019, alimony received is taxable income for the recipient and counts toward ACA MAGI. The Tax Cuts and Jobs Act of 2017 changed alimony treatment for agreements finalized on or after January 1, 2019: alimony is no longer income to the recipient and no longer deductible by the payor. For those newer agreements, alimony does not count toward ACA MAGI. Brokers should ask for the finalization date of any divorce agreement when a client mentions alimony.
Do Roth IRA distributions count toward ACA income?
Qualified Roth IRA distributions are not included in gross income and do not count toward ACA MAGI. A distribution is qualified when the account has been open at least five years and the owner is at least 59 and a half. This is a significant planning consideration for clients in the 60 to 64 window who can structure retirement income withdrawals to manage their ACA MAGI and protect their subsidy. Traditional IRA and 401(k) distributions, by contrast, are taxable and do count.
What is the difference between SSDI and SSI for ACA MAGI purposes?
SSDI (Social Security Disability Insurance) is an earned benefit funded by payroll taxes paid during working years. It is taxable income subject to the same 50 to 85 percent provisional income calculation as retirement Social Security, and the full gross benefit counts toward ACA MAGI. SSI (Supplemental Security Income) is a need-based program for adults with limited income and resources who are aged, blind, or disabled. SSI is not taxable and does not count toward ACA MAGI. The two programs are administered by the Social Security Administration but operate under different rules. Clients on SSDI often receive a regular monthly benefit; clients on SSI receive a needs-based payment, sometimes alongside SSDI if their SSDI benefit is low enough.
Does capital gains income count toward ACA MAGI?
Yes, net capital gains are included in adjusted gross income and count toward ACA MAGI. Both short-term and long-term capital gains apply. A client who sells a rental property, a large stock position, or a business during the plan year may see their MAGI jump enough to shift them across an FPL band, affecting their APTC and CSR tier for that year. The gain from selling a primary residence is excluded up to $250,000 for single filers and $500,000 for married filing jointly under the IRC Section 121 exclusion, and excluded gain does not count. Gains above those thresholds do count.
