NIIT, IRMAA, RMDs: Why Taxes Work Better as a Multi-year Plan

Looking only at this year’s bill can hide higher costs that show up later. The real job is to see how your income sources stack together over several years and to coordinate moves so this year’s fix does not cause next year’s surprise.

When income rises in the wrong year, the 3.8% Net Investment Income Tax (NIIT) can apply once modified AGI exceeds its thresholds. In retirement, Medicare’s income-related premium surcharge (IRMAA) looks back two years and even counts otherwise tax‑exempt interest.

A decision today can raise premiums in a future year if you do not plan for the look‑back. [1][5]

See the whole income stack before you act

Your return layers income from several places. Wages, dividends, and interest may be part of the stack. Realized gains, retirement distributions, Roth conversions, and pass-through income may be part of it too. Push too many layers into one year, and you may trigger NIIT on investment income above the threshold.

Hold the stack lower in a different year, and the same moves can land at better effective rates. [1]

Capital gains have their own system. Short‑term gains are taxed at ordinary rates. Long‑term gains get preferential brackets. Losses can offset gains, but the wash‑sale rule disallows a loss if you buy back a substantially identical security inside the 30‑day window before or after the sale.

These mechanics reward pacing and coordination more than one‑off plays. [2][3]

Dovetail Principle: Financial Decisions Need to Fit Together.

When you see how one move changes taxes, premiums, and future flexibility, judgment gets clearer.

Why one‑year tax plays can backfire

A year‑end tactic, like pulling deductions into December or realizing extra gains in a “low” year, can look smart in isolation. But next year’s adjusted gross income, Medicare premiums, or NIIT exposure can rise because of what you did this year. [1][5]

For example, realizing a large long‑term gain in the same year you convert to Roth can lift modified AGI above the NIIT threshold. That adds 3.8% on top of the applicable capital‑gains rate for the portion of net investment income above the threshold.

The same two moves spread across different years can avoid that stack. [1][2]

RMDs, Roth moves, and Medicare: how they connect

Required minimum distributions begin at age 73 under current rules and count as ordinary income. If RMDs land on top of dividends, gains, or business income, they can push you into higher brackets and increase IRMAA exposure two years later. [4][5]

Pre‑RMD Roth conversions can lower later required withdrawals and may reduce lifetime taxes when you convert in controlled bands that respect NIIT and IRMAA thresholds.

Conversions are taxable in the year you convert, and higher income can affect Medicare costs, so size them with the look‑back in view. [7][5]

Capital gains, NIIT, and harvest discipline

Long-term gains can be taxed differently until NIIT applies. Large gains realized in a year that already includes a bonus, a business surge, or a conversion can push modified AGI over the NIIT line.

A multi‑year gain‑realization plan, plus loss harvesting that respects wash‑sale rules, helps keep you in better bands and smooths exposure. [1][2][3]

Schedule portfolio moves alongside income and retirement‑account decisions. Avoid treating tax‑loss harvesting as a December project. The goal is the right income in the right year, not just a trade that looks good this week. [2][3]

Charitable giving that moves taxes now and later

Donating appreciated securities directly to a qualified charity or a donor‑advised fund can remove the embedded capital gain and generate an itemized deduction, subject to limits. It also lets you fund several years of grants in a single high‑income year while giving over time.

After age 70½, Qualified Charitable Distributions (QCDs) from IRAs can satisfy part or all of your RMD once RMDs begin and keep that amount out of AGI, which may help with both NIIT and IRMAA exposure.

Verify qualified‑organization status and deduction rules before you move. [6][8]

A practical rhythm to minimize lifetime taxes

• Map the next 3 to 5 tax years, not just this April. Note RMD start dates, equity‑comp vests, business variability, and likely sale events.
• Assign “bands and windows.” Mark where NIIT begins, where capital‑gains brackets shift, and where IRMAA steps change.
• Fit Roth conversions, gain realization, and charitable moves inside the best windows.

Avoid stacking big moves in one year. - Recheck annually. Rules, thresholds, markets, and your life change. A short review keeps the system working together and prevents next year’s bill from erasing this year’s win. [1][4][5]

About the Author

Ross Marino, CFP®, CeFT®, is the Founder & CEO of Dovetail Financial and creator of Human-First Financial Guidance®. He helps people nearing or living in retirement connect their lives and wealth so that financial decisions become clearer, more personal, and easier to navigate. 

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Notes

1. Internal Revenue Service, “Net Investment Income Tax,” accessed May 15, 2026. IRS
2. Charles Schwab, “Capital Gains Tax Rates: Short‑term vs. Long‑term,” updated 2026, accessed May 15, 2026. schwab.com
3. Legal Information Institute (Cornell Law School), “26 CFR § 1.1091‑1 — Losses from wash sales of stock or securities,” accessed May 15, 2026. law.cornell.edu
4. Kiplinger, “Required Minimum Distributions (RMDs): Rules, Deadlines, and SECURE 2.0 Changes,” updated Nov. 7, 2025, accessed May 15, 2026. kiplinger.com
5. Social Security Administration, “SSA Handbook §2501: What is Modified Adjusted Gross Income (MAGI)?” accessed May 15, 2026. Social Security Administration
6. Fidelity Charitable, “What is a qualified charitable distribution?” updated 2026, accessed May 15, 2026. fidelitycharitable.org
7. Charles Schwab, “3 Strategies to Help Ease Your RMD Tax Burden,” updated 2026, accessed May 15, 2026. schwab.com
8. Fidelity Charitable, “Bunching Charitable Donations,” accessed May 15, 2026. fidelitycharitable.org

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