Can a Roth Conversion Cause You to Pay the 3.8% Net Investment Income Tax?

You have $1.6 million in your traditional IRA.

You also have $800,000 in a brokerage account.

That brokerage account produces dividends, interest, and occasional capital gains.

You’re considering a $200,000 Roth conversion.

You already know the conversion can create ordinary taxable income.

Then your accountant mentions something else:

“We also need to check the Net Investment Income Tax.”

Your immediate reaction is:

“Why? My Roth conversion isn’t investment income.”

That’s where this gets interesting.

Your Roth conversion generally isn’t itself treated as net investment income for purposes of the federal Net Investment Income Tax.

But taxable retirement distributions can still affect the modified adjusted gross income side of the calculation.

So the conversion can potentially expose more of your actual investment income to the 3.8% tax without the conversion itself being net investment income.

Quick Answer: Does a Roth Conversion Trigger NIIT?

Not in the way most people think.

The taxable Roth conversion itself generally isn’t included in net investment income.

But the conversion can increase adjusted gross income.

That can increase modified adjusted gross income used for the NIIT threshold calculation.

If you also have net investment income, that combination can potentially increase your NIIT.

The conversion can affect the tax without being the income that is actually subject to the tax.

What Is the Net Investment Income Tax?

The Net Investment Income Tax is commonly called NIIT.

Under current federal law, the tax rate is 3.8%.

For an individual, the tax is generally calculated on the lesser of:

• Net investment income, or
• The amount by which modified adjusted gross income exceeds the applicable statutory threshold

Current statutory thresholds include:

• $250,000 for married taxpayers filing jointly
• $125,000 for married taxpayers filing separately
• $200,000 for single taxpayers and heads of household

Tax rules can change, so the current thresholds and calculations should be confirmed for the year of the conversion.

What Counts as Net Investment Income?

Depending on the circumstances, net investment income can generally include items such as:

• Interest
• Dividends
• Capital gains
• Rental income
• Royalty income
• Income from nonqualified annuities
• Certain passive business income

There are adjustments, exclusions, and special rules.

So don’t simply add every investment-related number on your tax return and assume that’s your NIIT amount.

What Generally Isn’t Net Investment Income?

IRA distributions are generally excluded from net investment income for NIIT purposes.

That distinction is critical.

If you convert $200,000 from a traditional IRA to a Roth IRA and the $200,000 is taxable, you shouldn’t simply calculate:

$200,000 × 3.8%.

That’s not how the NIIT calculation generally works.

The taxable conversion can affect the MAGI threshold calculation even though the conversion itself isn’t generally net investment income.

A Simple Example

Suppose a married couple filing jointly has:

• $190,000 of other income included in the relevant MAGI calculation
• $40,000 of net investment income
• No Roth conversion

Their total relevant income in this simplified example is below the current $250,000 married-filing-jointly NIIT threshold.

Now suppose they complete a taxable $100,000 Roth conversion.

Their income picture changes.

The conversion itself isn’t suddenly $100,000 of net investment income.

But it may push MAGI above the applicable NIIT threshold.

Now some or all of that $40,000 of actual net investment income may potentially be exposed to the 3.8% tax.

That’s the interaction you need to understand.

The Conversion Didn’t Create the Investment Income

This is the easiest way to think about it.

You already had the dividends.

You already had the capital gains.

You already had the rental income.

The Roth conversion didn’t create those items.

But the conversion may push your income high enough that the NIIT calculation starts applying to some of them.

Why This Matters for Someone With a Large Brokerage Account

Suppose you’re 60.

You have:

• $1.7 million traditional IRA
• $900,000 brokerage account
• $200,000 cash
• No pension
• Social Security planned later

Your brokerage account produces:

• Interest
• Dividends
• Capital gains

You decide to convert $250,000.

If you’re only looking at the ordinary federal income tax on the conversion, you may be missing part of the picture.

The conversion could also change how much of your existing net investment income is exposed to NIIT.

This Is Different From Saying “Roth Conversions Are Subject to NIIT”

That statement is too broad.

And potentially misleading.

The better question is:

“Will the taxable conversion increase my MAGI enough to change the NIIT on my other investment income?”

That’s what should be modeled.

What If You Don’t Have Any Net Investment Income?

Then the NIIT may not be the issue you’re worried about.

Remember the tax is based on the lesser of net investment income or MAGI above the applicable threshold.

If there’s no net investment income, simply having income above the threshold doesn’t automatically create NIIT on ordinary Roth conversion income.

Crossing the threshold alone doesn’t turn your Roth conversion into net investment income.

What If You Have a Large Capital Gain?

Now the interaction can become more significant.

Suppose you sell appreciated investments.

You realize a substantial capital gain.

Then you add a large Roth conversion in the same year.

The capital gain may be part of net investment income, while the Roth conversion may increase MAGI.

Those two events can collide inside the NIIT calculation.

That doesn’t automatically mean you shouldn’t convert.

It means the conversion should be evaluated with the gain included.

What If You Sold a Rental Property?

Same concept.

A property sale can potentially create investment income and capital gain considerations.

You may also have rental income during the year.

Then you add a Roth conversion.

Now you’re not evaluating one tax event.

You’re stacking several events into the same tax year.

The Roth conversion number should be chosen after those events are included, not before.

What If You Still Own Rental Properties?

Rental income can potentially be included in net investment income, subject to the applicable rules and your level of participation.

That makes NIIT especially worth checking for retirees who have:

• Large traditional IRAs
• Rental properties
• Brokerage assets
• Interest and dividends

A conversion strategy that ignores the rest of the tax return can produce a misleading result.

What About Dividends?

Dividends can be part of net investment income.

For someone with a large taxable portfolio, annual dividend income may be substantial even without selling anything.

You could have $30,000, $50,000, or more of investment income before deciding to convert a single IRA dollar.

That existing income needs to be included in the Roth conversion analysis.

What About Interest Income?

Interest can also be part of net investment income under applicable rules.

This has become more relevant for retirees holding substantial amounts in:

• CDs
• Money market funds
• Bonds
• High-yield savings accounts

A large cash reserve can generate meaningful taxable interest.

Then a Roth conversion raises the broader income picture.

What About Social Security?

Social Security benefits aren’t generally treated as net investment income for NIIT purposes.

But Roth conversion income can separately affect the federal calculation determining how much of your Social Security benefits is included in taxable income.

So someone taking Social Security may have multiple income interactions happening at once.

NIIT is only one of them.

What About Pension Income?

Traditional pension income isn’t simply the same thing as net investment income for NIIT purposes.

But pension income can contribute to the broader income picture.

If you already have significant pension income, you may have less room before additional taxable Roth conversion income changes other tax calculations.

What About RMDs?

IRA distributions aren’t generally included in net investment income for NIIT purposes.

But taxable IRA distributions can still affect MAGI used for the NIIT threshold.

That means future RMDs can potentially create a similar interaction with your investment income.

This creates an interesting long-term Roth conversion question:

Could paying conversion tax earlier reduce future traditional IRA balances enough to improve the later income picture?

Maybe.

But that future potential benefit has to be compared against the current conversion cost.

Example: Do Nothing Versus Convert Earlier

Imagine you’re 62.

You have:

• $2 million traditional IRA
• $1 million taxable investment account
• $250,000 cash
• Social Security planned later
• No pension

Your taxable portfolio produces meaningful dividends, interest, and capital gains.

One strategy is to leave the IRA alone.

Another is to complete measured Roth conversions over several years.

The conversion years may increase current taxable income and potentially affect NIIT.

But reducing the traditional IRA may also change future RMDs and future income.

You have to compare both sides of the timeline.

Don’t Avoid $1 of NIIT by Creating $10 of Another Problem

This is where tax planning can go off the rails.

Someone sees the 3.8% tax and becomes obsessed with avoiding it.

Then they reject a Roth conversion strategy that may have produced a stronger overall modeled result.

Or they reduce the conversion so much that future RMDs become significantly larger.

The goal isn’t:

“Never pay NIIT.”

The goal is:

“Which strategy produces the strongest overall projected retirement result after considering the relevant taxes and tradeoffs?”

What If a Smaller Conversion Keeps You Below the NIIT Threshold?

That’s a scenario worth testing.

Suppose you’re considering $200,000.

We might also test:

• $50,000
• $100,000
• $125,000
• $150,000
• $200,000
• No conversion

Maybe one conversion amount creates a noticeably different NIIT result.

Then we can see whether stopping below that point actually improves the long-term retirement projection.

What If Crossing the Threshold Only Costs a Little?

Then refusing to cross it may make no sense.

This is why thresholds can create bad behavior.

You hear:

“If we cross $250,000, there’s another 3.8% tax.”

And your brain hears:

“Everything is taxed another 3.8%.”

That’s not generally how the NIIT calculation works.

The actual tax is based on the statutory formula.

Calculate the incremental cost instead of being scared by the name of the tax.

NIIT Is Not the Same as the Additional Medicare Tax

This is another common source of confusion.

The Net Investment Income Tax and the Additional Medicare Tax are separate federal taxes.

They apply to different categories of income under different rules.

Don’t combine them into one generic “Medicare tax” assumption.

NIIT Is Also Not the Same as Medicare IRMAA

These are completely different calculations.

NIIT is a federal income tax.

IRMAA can increase Medicare Part B and Part D premiums based on applicable income rules.

A large Roth conversion can potentially affect both calculations, but through different systems.

If you’re on Medicare and also have substantial investment income, both should be checked.

One Conversion Can Touch Several Parts of the Tax Return

Imagine a retiree who has:

• Social Security
• Dividend income
• Interest income
• Capital gains
• Rental income
• Medicare
• A $200,000 Roth conversion

Asking only:

“What tax bracket does the conversion land in?”

doesn’t tell the whole story.

You need to see what happens to the broader tax picture.

The Emotional Trap: “I Don’t Want to Trigger Another Tax”

This is understandable.

You spent 40 years paying taxes.

Now you’re retired.

You finally have control over some of your taxable income.

Then someone tells you a voluntary Roth conversion could cause another tax to appear.

Your reaction is:

“Then I’m not doing it.”

But that’s a conclusion before the math.

Maybe the incremental NIIT is small.

Maybe it’s substantial.

Maybe reducing the conversion solves it.

Maybe paying it now still produces the stronger long-term projection.

You need the number before you need the opinion.

“We Should Be Able to Handle This Ourselves”

You know your income.

You know your brokerage account.

You know how much you want to convert.

You think:

“We should be able to handle this ourselves.”

Then you discover that the Roth conversion isn’t net investment income but can still affect the NIIT calculation.

Then capital gains enter the picture.

Then Medicare enters the picture.

Then Social Security enters the picture.

That’s when the simple question becomes a tax-coordination problem.

“I Don’t Want to Ask My Kids for Help”

Maybe the conversion looks attractive long term.

But the conversion tax, NIIT, Medicare effects, and other taxes consume more cash than expected.

Now your emergency reserve is smaller.

You think:

“I don’t want to ask my kids for help.”

Then the strategy needs to protect current liquidity as well as future tax efficiency.

A tax strategy that leaves you uncomfortable writing a $30,000 emergency check isn’t automatically a better retirement strategy.

“What If We Mess This Up and Regret It?”

You don’t want to convert too much and create taxes you didn’t anticipate.

You don’t want to convert too little and watch the traditional IRA keep growing.

You don’t want future RMDs creating the same problem later.

You don’t want to make an irreversible conversion based on one tax calculation while ignoring three others.

You think:

“What if we mess this up and regret it?”

That’s why the answer isn’t a rule of thumb.

It’s scenario comparison.

What If You’re Married?

Filing status matters to the NIIT calculation.

It can also matter enormously later if one spouse dies.

A married couple may be comfortable under one income structure.

The surviving spouse may eventually file under a different status and face different tax thresholds.

That’s why the Roth conversion analysis shouldn’t stop at the couple’s current-year return.

The Surviving-Spouse Problem

Suppose one spouse dies later in retirement.

The surviving spouse may still have:

• Traditional retirement accounts
• RMDs
• Social Security
• Interest
• Dividends
• Capital gains
• Rental income

But the household’s filing status and applicable thresholds may change.

Earlier Roth conversions could potentially alter that future income picture.

Again, the current conversion cost has to be compared against the projected future result.

Should NIIT Determine Your Roth Conversion Amount?

It should be a variable.

Not necessarily the boss.

If a conversion creates additional NIIT, include it.

If reducing the conversion avoids some NIIT, test that.

If paying some NIIT produces a stronger long-term result, test that too.

Don’t let one tax threshold dictate a 20-year retirement strategy without making the alternatives compete.

How Can the Roth Conversion Tax Be Addressed?

If the conversion also changes NIIT, that potential tax belongs in the cash-flow calculation.

Option 1: Outside Cash or Taxable Assets

Outside assets may be used to address taxes generated by Roth conversions.

This can allow more of the selected conversion amount to reach or remain inside the Roth.

But selling taxable investments to raise cash can itself potentially create gains.

Those gains may affect the broader tax and NIIT calculation.

The account used to pay the tax can sometimes change the tax calculation too.

Option 2: Retirement Assets or Withholding

Another approach may involve retirement assets or withholding.

This can reduce the amount ultimately reaching or remaining inside the Roth and may create additional tax considerations.

The mechanics and tax consequences should be reviewed before the transaction.

Option 3: Contractual Carrier Bonus Value

When suitable, certain annuity contracts may provide contractual carrier bonus value that can be included in the broader economic comparison.

In some modeled scenarios, contractual carrier bonus value may economically offset some or potentially all of the conversion-tax cost over the strategy period.

This may potentially reduce the need for additional personal out-of-pocket cash from an overall economic standpoint.

The carrier does not assume your IRS tax liability.

A carrier bonus isn’t an IRS tax credit.

It also doesn’t eliminate NIIT or another federal tax liability.

Your taxes remain your responsibility.

Bonus terms, vesting, surrender provisions, liquidity restrictions, charges, participation rates, caps, spreads, crediting methods, income features, guarantees, and other contractual provisions need to be evaluated.

This Is Where Roth Blueprint Software Comes In

If you have substantial taxable investments, I don’t want to look at the Roth conversion in isolation.

We need to know what else is happening.

Using our Roth Blueprint software, we can assess thousands of potential modeled Roth conversion scenarios within the broader retirement picture.

The goal isn’t to find the biggest conversion.

It’s to find the conversion strategy that produces the strongest modeled result after the relevant assumptions are included.

What Can We Compare?

We can assess different:

• Traditional retirement balances
• Roth balances
• Conversion amounts
• Conversion starting years
• Multi-year conversions
• Variable annual conversions
• No conversion
• Investment-income assumptions
• Capital-gain assumptions
• Projected conversion taxes
• Potential NIIT considerations
• Different approaches to addressing conversion taxes
• Retirement spending
• Outside liquidity
• Social Security timing
• Pension income
• Potential healthcare-related income considerations
• Projected RMDs
• Surviving-spouse outcomes
• Beneficiary outcomes
• Legacy outcomes

Example: Make the NIIT Threshold Compete With the Long-Term Plan

Imagine you’re 63.

You have:

• $1.8 million traditional IRA
• $900,000 brokerage account
• $250,000 cash
• Meaningful annual dividends and interest
• Occasional capital gains
• Social Security planned later

We might compare:

Scenario A: No Roth conversion.

Scenario B: A conversion amount designed to remain below a particular modeled income level.

Scenario C: A larger conversion that may create some additional NIIT but reduces more of the traditional IRA.

Scenario D: Smaller conversions spread over additional years.

Scenario E: Variable conversions based on annual investment income, realized gains, Social Security, Medicare, liquidity, and projected RMDs.

Then we compare:

• Current projected taxes
• Potential NIIT
• Traditional balances
• Roth balances
• Future RMDs
• Retirement income
• Liquidity
• Potential Medicare considerations
• Surviving-spouse outcomes
• Beneficiary outcomes
• Legacy outcomes

Now we can see whether avoiding NIIT actually improves the retirement plan or merely makes one line on this year’s tax return look better.

The Retirement Math Method™

This is why we use our Retirement Math Method™.

I don’t start with:

“Stay under the NIIT threshold at all costs.”

I don’t start with:

“NIIT doesn’t matter because the conversion isn’t investment income.”

Both are too simplistic.

The conversion itself generally isn’t net investment income.

But the taxable conversion can still affect the MAGI side of the NIIT calculation.

So we put it into the math.

Maybe staying below the threshold wins.

Maybe crossing it slightly wins.

Maybe a larger conversion and some additional current tax produces a stronger long-term result.

Maybe smaller conversions win.

Maybe variable conversions win.

Maybe doing nothing wins.

I don’t try to sell you on the strategy. I make the strategy prove itself with the math.

Let the math do the talking.

Frequently Asked Questions About Roth Conversions and NIIT

Is a Roth conversion subject to the 3.8% Net Investment Income Tax?

IRA distributions are generally excluded from net investment income for NIIT purposes. However, taxable retirement distributions can affect modified adjusted gross income used in determining whether the NIIT applies to other net investment income.

Can a Roth conversion increase my NIIT?

Potentially. If you have net investment income, additional taxable income from a Roth conversion may increase the amount by which MAGI exceeds the applicable NIIT threshold, potentially increasing the tax.

What is the NIIT rate?

Under current federal law, the Net Investment Income Tax rate is 3.8%.

What are the NIIT income thresholds?

Under current federal law, the statutory thresholds for individuals generally include $250,000 for married filing jointly, $125,000 for married filing separately, and $200,000 for single or head-of-household filers. Current rules should be confirmed for the tax year being analyzed.

Are capital gains included in net investment income?

Capital gains can generally be included in net investment income, subject to applicable exclusions, adjustments, and other federal tax rules.

Are dividends included in net investment income?

Dividends can generally be included in net investment income under applicable federal rules.

Is rental income subject to NIIT?

Rental income can potentially be included in net investment income, but the treatment can vary based on the taxpayer’s circumstances, activity, and applicable tax rules.

Is Social Security included in net investment income?

Social Security benefits aren’t generally included in net investment income for NIIT purposes.

Is NIIT the same as Medicare IRMAA?

No. NIIT is a federal tax on certain net investment income under its own rules. IRMAA is an income-related adjustment that can increase Medicare Part B and Part D premiums. A Roth conversion can potentially affect both calculations differently.

Can Roth Blueprint account for NIIT?

Our Roth Blueprint process can assess thousands of potential modeled Roth conversion scenarios using relevant tax, income, investment, liquidity, Social Security, Medicare, RMD, surviving-spouse, beneficiary, and other retirement assumptions. Actual NIIT liability should be determined with a qualified tax professional.

Don’t Ask Only What Tax the Conversion Creates

Ask what the conversion changes.

That’s the better question.

It can change:

• Current taxable income
• Available cash
• Future traditional IRA balances
• Future Roth balances
• Projected RMDs
• Social Security taxation calculations
• Medicare premium calculations
• Potential NIIT
• The surviving spouse’s future tax picture

The conversion is one transaction. The consequences can spread across the entire retirement plan.

Have a Large IRA Plus Significant Investment Income? Let’s Run the Math.

If you have $500,000, $750,000, $1 million, $2 million, or more in traditional IRAs, 401(k)s, or other tax-deferred retirement assets and also have substantial brokerage assets, capital gains, dividends, interest, rental income, or other investment income, NIIT deserves a place in the Roth conversion conversation.

When you meet with me, we can use our Roth Blueprint software and Retirement Math Method™ to assess thousands of potential modeled scenarios.

We can compare:

• No Roth conversion
• Smaller annual conversions
• Larger annual conversions
• Multi-year conversions
• Variable annual conversions
• Different investment-income assumptions
• Different capital-gain assumptions
• Projected conversion taxes
• Potential NIIT considerations
• Different approaches to addressing conversion taxes
• Retirement spending
• Personal liquidity
• Social Security timing
• Pension income
• Potential healthcare-related income considerations
• Projected traditional balances
• Projected Roth balances
• Projected RMDs
• Retirement income
• Surviving-spouse outcomes
• Beneficiary outcomes
• Legacy outcomes

Then we put the strategies side by side.

Maybe staying below a particular income threshold wins.

Maybe paying some additional NIIT while converting more produces the stronger projected result.

Maybe smaller conversions spread over more years win.

Maybe variable conversions based on annual investment income win.

Maybe doing nothing wins.

That’s what you want to know before rejecting a Roth conversion simply because you heard the words “3.8% investment tax.”

We don’t sell you a retirement strategy. We run the math and let you decide.

Let the math do the talking.

Schedule Your Roth Conversion Strategy Appointment

Explore More

• 
  Should I Do a Roth Conversion in the Same Year as a Large Capital Gain?
  
• 
  Should I Do a Roth Conversion If I Have a Large Brokerage Account?
  
• 
  Should I Do a Roth Conversion If I Have Rental Property Income?
  

Important Disclosure

This article is for educational purposes only and isn’t intended as individualized tax, legal, accounting, investment, insurance, Medicare, Social Security, estate-planning, or retirement-planning advice. FPP Financial does not provide tax or legal advice. Under current federal rules, the Net Investment Income Tax is generally 3.8% of the lesser of an individual’s net investment income or the amount by which modified adjusted gross income exceeds the applicable statutory threshold. Net investment income can include interest, dividends, capital gains, rental and royalty income, nonqualified annuity income, and certain passive business income, subject to applicable exclusions, deductions, adjustments, and other rules. Distributions from IRAs and certain qualified retirement plans are generally excluded from net investment income for NIIT purposes, but taxable retirement distributions can be taken into account when determining modified adjusted gross income for the NIIT threshold calculation. Therefore, a taxable Roth conversion may potentially increase NIIT on other net investment income without the conversion itself being treated as net investment income. The actual NIIT calculation is taxpayer-specific and should be determined using current law and applicable tax forms, including Form 8960 when required. Roth conversions generally create taxable income to the extent converted amounts would otherwise be taxable. Qualified Roth IRA distributions are generally tax-free under current federal rules when applicable requirements are satisfied. Taxable Roth conversion income can affect federal and state income taxes, marginal tax rates, the federal calculation determining how much of Social Security benefits is included in taxable income, ACA Marketplace premium tax credits when applicable, Medicare premiums, estimated tax requirements, liquidity, NIIT calculations, beneficiary outcomes, and other parts of a financial plan. Required minimum distribution starting ages and rules vary based on birth year, account type, beneficiary status, and current law. An amount required to be distributed as an RMD for the year isn’t eligible for Roth conversion. Roth conversions can potentially reduce future traditional retirement-account balances and future RMDs relative to an otherwise identical no-conversion scenario, but no specific tax, NIIT, investment, Medicare, Social Security, RMD, retirement-income, surviving-spouse, beneficiary, liquidity, or legacy outcome is guaranteed. Tax laws, NIIT thresholds, retirement-account rules, Social Security rules, Medicare rules, estate rules, beneficiary rules, and investment values can change. Roth Blueprint calculations and other projections are based on assumptions and information entered into the analysis and aren’t guarantees of future tax results, NIIT liability, account values, investment performance, retirement income, Medicare premiums, Social Security outcomes, RMD reductions, surviving-spouse outcomes, beneficiary outcomes, legacy results, liquidity, or product performance. Insurance and annuity products may contain fees, charges, surrender periods, liquidity restrictions, eligibility requirements, bonus provisions, participation rates, caps, spreads, crediting methods, income features, guarantees, and other contractual terms. Guarantees are subject to the claims-paying ability of the issuing insurer. A carrier bonus isn’t an IRS tax credit and doesn’t transfer the client’s tax liability to an insurance company. Statements that contractual carrier bonus value may economically offset some or potentially all of a modeled conversion-tax cost aren’t statements that the tax disappears or that the carrier directly pays the client’s tax liability. Before completing a Roth conversion, realizing capital gains, selling investments or real estate, taking retirement distributions, changing investment holdings, using outside assets to address taxes, purchasing an insurance or annuity product, or making other retirement decisions, consider working with qualified tax, legal, accounting, financial, investment, insurance, Medicare, Social Security, estate-planning, and other appropriate professionals who can evaluate your individual circumstances and current rules.