Question 1

What is a MAGI phase-out?

Accepted Answer

A MAGI phase-out is the income range over which a tax benefit gradually disappears. Modified adjusted gross income, or MAGI, is your adjusted gross income with certain items added back, such as tax-exempt interest or a foreign earned income exclusion. Once your MAGI crosses the lower edge of a phase-out range, the benefit starts shrinking, and once you pass the upper edge it is gone entirely. Different tax breaks use different MAGI definitions and different thresholds, which is why one income figure can affect several of them at once.

Question 2

What is the difference between a phase-out and a tax cliff?

Accepted Answer

A phase-out is a slope: the benefit fades gradually across an income range, so earning one more dollar costs only a small fraction of the benefit. A cliff is a hard edge: crossing a single threshold by one dollar triggers the full consequence. The Medicare IRMAA surcharge is the classic cliff, because one dollar over a bracket applies the entire surcharge for the year. The 3.8% net investment income tax and the 0.9% additional Medicare tax behave more like slopes, since they only apply to the income above the threshold, not your whole income.

Question 3

What are the 2026 Roth IRA income limits?

Accepted Answer

For 2026, the Roth IRA contribution phase-out runs from $153,000 to $168,000 of MAGI for single and head-of-household filers, and from $242,000 to $252,000 for married couples filing jointly. Below the lower number you can contribute the full amount, inside the range your allowed contribution shrinks, and above the upper number direct contributions are not allowed. Many higher earners use a backdoor Roth, contributing to a Traditional IRA and converting, to get around the limit.

Question 4

How does the IRMAA Medicare surcharge cliff work?

Accepted Answer

IRMAA adds a surcharge to your Medicare Part B and Part D premiums when your income is above a set threshold. It uses your MAGI from two years earlier, so your 2024 income determines your 2026 surcharge. For 2026 it starts above $109,000 for single filers and $218,000 for joint filers. It is a true cliff: crossing a bracket by even one dollar applies the full surcharge for the entire year, and it applies to each spouse on Medicare separately. The top bracket adds nearly $580 a month per person across Part B and Part D.

Question 5

What income triggers the 3.8% net investment income tax?

Accepted Answer

The net investment income tax, or NIIT, is an extra 3.8% on investment income such as interest, dividends, capital gains, and rental income. It applies once your MAGI passes $200,000 for single and head-of-household filers or $250,000 for married couples filing jointly. These thresholds are set in statute and are not adjusted for inflation, so more households cross them every year. The tax applies to the smaller of your net investment income or the amount of MAGI above the threshold, not to your entire income.

Question 6

How can I avoid losing tax benefits to phase-outs?

Accepted Answer

The lever is your MAGI, so anything that lowers it can keep a benefit alive. Maxing a Traditional 401k, an HSA, or a deductible Traditional IRA reduces AGI. Harvesting capital losses, deferring a bonus, bunching deductions, or spreading a Roth conversion across years can keep you under a cliff. Retirees managing IRMAA often plan Roth conversions and capital gains two years ahead, since today’s income sets the surcharge two years out. The goal is rarely to earn less, but to time and shape income so you do not pay full price to cross a line by a small amount.

MAGI Phase-Out Dashboard

Why one income number trips so many wires