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Capital Gains Tax Calculator — Married Filing Separately 2025

Married filing separately uses narrower brackets. The NIIT MAGI threshold is generally $125,000 for MFS — half of the joint threshold.

Capital Gains Calculator

Federal · NIIT · All 50 states

2026 ratesIRS verified

Follow the three steps, save the sale, then calculate. Required fields are marked with *.

Your tax profile

These apply to every sale in this estimate.

What you sold

Prices and quantity for this lot. Give it a name if you will add more than one sale.

Asset type

When you bought and sold

The IRS uses these dates to decide short-term vs long-term rates.

Next: Save this sale to the order log, then click Calculate now. Tax results do not update until you calculate.

Order log

Sales included in this tax estimate.

Please fill in the details to see your results. Follow the three steps on the left, then save a sale here.

Married filing separately capital gains

Married filing separately (MFS) uses brackets that are typically half of joint amounts for many preferential thresholds, and the NIIT MAGI threshold is generally $125,000 — intentionally lower so couples cannot avoid the surtax by filing separately at the full joint threshold.

MFS can be appropriate in limited cases (for example certain liability separations or itemised-deduction interactions), but it often produces a higher combined tax than MFJ for investment gains. Community-property states may require special income allocation rules even when filing separately.

Compare MFS vs MFJ estimates carefully, including NIIT and state interactions. Our calculator lets you switch filing status while holding the same gain inputs.

Not tax advice. Confirm filing-status choice with a CPA when the decision is close or when state community-property rules apply.

Comparesingle,married filing jointly,head of household, andmarried filing separately·Methodology

FAQ

Frequently asked questions

Why is the MFS NIIT threshold lower?

Section 1411 sets the married filing separately MAGI threshold at $125,000 so the surtax cannot be avoided by filing separately at the full joint threshold.

Is MFS usually worse for capital gains?

Often yes — narrower preferential brackets and the lower NIIT threshold can increase tax versus MFJ. Exceptions exist; model both statuses.

Do community-property states change MFS results?

They can. Community-property rules may require splitting certain income even when spouses file separately. State rules vary — get local advice.