Finance category
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NIIT Calculator
NIIT (3.8%) applies to net investment income for single filers over $200K MAGI or joint filers over $250K. Common hit: rental profit, cap gains at sale, dividends, interest. This calculator sizes the liability. NIIT thresholds haven't been inflation-indexed since enactment in 2013. Effective tax creep has pulled more taxpayers into NIIT each year. Strategies to reduce: increase tax-advantaged retirement contributions to drop MAGI below threshold, time capital gain realizations across tax years, use real estate professional status to recharacterize rental income as non-passive, or employ tax-loss harvesting to offset investment income.
NIIT owed
$2,660
Taxable base (lesser of excess or inv income)
$70,000
Total investment income
$77,000
MAGI excess over threshold
$70,000
Your threshold
$250,000
How the math works
Joint $320K MAGI: excess $70K. Total inv income: $77K. Taxable base = lesser = $70K × 3.8% = $2,660 NIIT.
Pay quarterly via estimated tax to avoid penalty. Strategies to reduce: REPS qualification for rentals, 1031 exchanges to defer caps, Roth conversions to reduce future investment income exposure.
EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.
Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.
Learn more about our review process on the EveryCalc methodology page.
How this calculator works
What this page estimates
This NIIT Calculator is built to give a quick, browser-based estimate for niit. NIIT (3.8%) applies to net investment income for single filers over $200K MAGI or joint filers over $250K. Common hit: rental profit, cap gains at sale, dividends, interest. This calculator sizes the liability. NIIT thresholds haven't been inflation-indexed since enactment in 2013. Effective tax creep has pulled more taxpayers into NIIT each year. Strategies to reduce: increase tax-advantaged retirement contributions to drop MAGI below threshold, time capital gain realizations across tax years, use real estate professional status to recharacterize rental income as non-passive, or employ tax-loss harvesting to offset investment income. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.
Calculation approach
The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For finance tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.
Example workflow
For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.
Practical checks
- Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
- Run a low, base, and high case when the inputs are estimates.
- Check the related calculators below when the next decision depends on a different assumption.
How to interpret the niit result
Best use
Use the result as a planning number for comparing payments, rates, returns, tax reserves, or cash-flow choices before you request a quote or make a commitment.
Cross-check
Compare the answer with the contract, lender estimate, tax form, brokerage statement, payroll record, or invoice that will control the real-world outcome.
Watch for
Do not rely on a single optimistic rate, return, or fee assumption. Money pages work best when you run low, base, and high cases and keep professional advice separate from the estimate.
This page belongs to the Finance calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.
Before relying on this niit estimate
Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.
Confirm source numbers
Match balances, rates, fees, taxes, income, and payment dates against the lender quote, payroll record, tax form, statement, invoice, or contract.
Separate cash flow from total cost
A lower monthly payment can still cost more over time if fees, interest, taxes, or a longer term are hidden in the structure.
Run conservative cases
Test at least one higher-cost or lower-return case before using the output for a purchase, refinance, investment, loan, or tax decision.
Rerun this page when the rate, price, term, fee, tax rule, income, expense, or expected holding period changes.
How to Use
- Enter MAGI and filing status.
- Enter investment income components.
- See NIIT owed.
Frequently Asked Questions
Who pays NIIT?
Single/HoH: MAGI over $200K. Joint: $250K. MFS: $125K. Thresholds NOT indexed for inflation. Trusts/estates also liable over $14,450.
Can I avoid it?
Real estate professional status (REPS) — if you qualify, rental income is 'non-passive' and might avoid NIIT. Also: 1031 exchange defers the tax on gains. Retirement account income is exempt.
What counts as investment income?
Rental net, cap gains, dividends, interest, royalties, annuity income. NOT: wages, self-employment income, active business income.
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