Social Security: What is the Difference Between "Income-Related Monthly Adjustment Amount" and "Modified Adjusted Gross Income"

Ask Rusty - Was Your IRMAA Article Incorrect?

Dear Rusty: In a recent article about Medicare's "Income-Related Monthly Adjustment Amount" (IRMAA) and how IRMAA affects Social Security taxes, you described which income gets included in the IRMAA calculation. You said it is "your combined income from all sources, including 50 % of the SS benefits you receive." That 50% number might be true in some cases, but I think a more accurate, general answer is that "your taxable SS benefit is what gets added to IRMAA." For example, we have enough income every year that we are always taxed at 85% of our SS benefit, so 85% of our SS values get added to our IRMAA. The way your answer reads, a reader of the article might think everyone has 50% of their SS benefit added to IRMAA. Signed: IRMAA Victim

Dear IRMAA Victim: I think you may have confused two terms I used when describing Medicare's "Income-Related Monthly Adjustment Amount" or "IRMAA." I also used the term "MAGI" (Modified Adjusted Gross Income), and it's important to distinguish between those two terms.

· MAGI is what determines if the IRMAA provision applies, and IRMAA will affect how much your Medicare premium is. But MAGI is also used for another purpose - to see if your SS benefits are taxable. Your MAGI consists of your Adjusted Gross Income (AGI) from your income tax return, plus any non-taxable interest you may have had, plus 50% of the SS benefits you received during the tax year

· IRMAA is a factor which will increase your monthly Medicare premium if your MAGI is over certain thresholds for your tax filing status. MAGI is used to determine if a higher Medicare premium applies, and it is also used to see if your SS benefits are subject to income tax.

Your MAGI does, indeed, always use only 50% of the SS benefits you received during the tax year (not 85% in some cases). That's because the SS contributions included in MAGI relate to SS contributions your employer paid on your behalf. Only half of your received SS benefits are used to determine MAGI because that's the amount of your SS benefits attributable to your employer's contributions. Said another way, the SS payroll tax you personally paid while working was from your taxable income, so it is not included in MAGI. But the amount your employer contributed was not taxable by the IRS and, thus, is included in MAGI. So, it's the portion of your SS benefits attributable to your employer which is included in MAGI. Thus, the terminology that MAGI is "your combined income from all sources, including 50% of the SS benefits you received during the tax year" is correct. MAGI is what determines how much of your SS benefits are taxable, but your MAGI also determines if IRMAA applies to your Medicare premiums.

Your benefits are taxable if, as a married couple filing jointly, your total MAGI exceeds $32,000. If your MAGI is over the first threshold but less than the 2nd threshold ($44,000 for married filers) then 50% of the SS benefits you received during the tax year are included as part of your income taxable by the IRS. But if your MAGI goes over the 2nd threshold ($44,000 for married filers) then up to 85% of the SS benefits you received during the tax year will be included as part of your income taxable by the IRS.

In short, MAGI determines how much of your income is subject to taxation. But MAGI is also used to determine if IRMAA applies. And how much your MAGI exceeds the separate IRMAA thresholds determines what your Medicare premium will be.

So, the article correctly states that IRMAA only counts 50% of the SS benefits received because that is what is included in MAGI (which is what determines if IRMAA applies). But the amount of SS which may be taxable income by the IRS could be up to 85% of benefits received during the tax year if your MAGI is high enough.

This article is intended for information purposes only and does not represent legal or financial guidance. It presents the opinions and interpretations of the AMAC Foundation's staff, trained and accredited by the National Social Security Association (NSSA). NSSA and the AMAC Foundation and its staff are not affiliated with or endorsed by the Social Security Administration or any other governmental entity. To submit a question, visit our website (amacfoundation.org/programs/social-security-advisory) or email us at ssadvisor@amacfoundation.org.

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