Capital Gains Sale Planner: Sell Now, Wait, or Choose Different Tax Lots
Plan a stock, fund or crypto sale by the tax it actually triggers \u2014 compare selling now, waiting for long-term treatment, harvesting losses, and choosing which tax lots to sell.
Scenarios
federal-capital-gains-1 · tax years 2025–2026.Tax-only break-even price
Long-term gain by rate band
Tax waterfall
| Line | Amount | Status |
|---|---|---|
| Sale price minus selling costs net proceeds | $70,000 | Derived |
| Adjusted basis (purchase + costs + adjustments) | $40,000 | Derived |
| Realized gain or loss | $30,000 | Derived |
| Short-term net after sale | $0 | Derived |
| Long-term net after sale | $30,000 | Derived |
| Baseline regular federal tax without the sale | $14,714 | Rule |
| After-sale regular federal tax with the sale | $19,214 | Rule |
| Incremental regular federal tax the difference | $4,500 | Derived |
| Incremental NIIT (3.8%) | $0 | Rule |
| Optional rough state estimate user rate | $1,500 | User input |
| Total estimated tax impact | $6,000 | Derived |
| After-tax proceeds | $64,000 | Derived |
- The tax attributed to the sale is the after-sale minus baseline difference, not the gain times a rate.
- State tax is an optional rough estimate from your entered rate, shown separately — not a state-tax engine.
- Not modeled: QSBS/§1202, collectibles, §1250 recapture, home-sale exclusion, AMT, kiddie tax, installment sales, Opportunity Zones.
- Confirm figures against current IRS guidance and consult a qualified professional before acting.
Tax-lot comparison (advanced)
Add up to 50 lots. Choose a target, then compare selection strategies. Uses marginal-rate estimates from your Sale details above.
| # | Acquisition date | Shares | Cost / share | |
|---|---|---|---|---|
| 1 | ||||
| 2 |
#), which your browser never sends to a server. Anyone with this link can read the values encoded in it. Inputs are never sent to analytics.Assumptions and Limitations
Assumptions
- You are a US individual selling an ordinary capital asset (stock, ETF, fund, bond or crypto) with no special rate.
- The tax attributed to the sale is the difference between the after-sale and baseline scenarios, not a single rate times the gain.
- Ordinary taxable income is your taxable income excluding the qualified dividends and net capital gains entered here.
- Long-term means held more than one year; the holding period begins the day after purchase.
- State tax is an optional rough estimate from the rate you enter and never changes the federal figures.
Limitations
- Not tax advice, a filing, or a guaranteed figure; it is an educational estimate from the values you enter.
- Does not model Section 1202/QSBS, collectibles, Section 1250 recapture, the primary-residence exclusion, AMT, kiddie tax, installment sales or Opportunity Zones.
- Does not implement any of the 50 states\u2019 specific tax rules; the state figure is a flat rough estimate from your entered rate only.
- The tax-lot comparison uses marginal-rate estimates to rank strategies consistently, not a full worksheet per lot subset.
- NIIT is estimated as 3.8% of the lesser of net investment income and MAGI over the statutory threshold; MAGI interactions beyond the sale are not modeled.
Baseline vs after-sale: why the tax is a difference, not a rate
The tax attributed to a sale is the change it makes to your whole-year federal tax: compute the year without the sale, then with it, and take the difference. That is what this planner does.
This matters because a gain stacks on top of your other income. The same $30,000 long-term gain can be taxed at 0%, 15%, 18.8% (with NIIT) or 20% depending on where it lands \u2014 a single headline rate cannot capture that.
The 0% long-term band and holding period
Long-term gains that stack within the 0% band are taxed at 0% federally. The planner shows how much additional long-term gain you could realize before regular federal capital-gains tax begins, after your ordinary income, qualified dividends and existing long-term gains fill the space first.
A gain is long-term only when held more than one year. When a sale is short-term, the planner shows the first long-term date and the tax you would save by waiting until then at the same price, plus the price decline you could absorb and still net the same after tax.
Tax-loss harvesting and the wash-sale rule
Selling a position at a loss can offset gains and reduce the tax on this sale. The planner shows how much loss would offset the proposed gain and the estimated federal tax that would save.
Beware the wash-sale rule: if you buy a substantially identical security within 30 days before or after the loss sale, the loss is disallowed. This applies across your taxable accounts, purchases by your spouse, and purchases in your IRA. The planner flags the rule but does not suggest specific replacement securities.
Long-term capital gains breakpoints (taxable income) by year and status
Taxable income where the 0% long-term rate ends (15% begins) and where 15% ends (20% begins). The rate on a long-term gain depends on total taxable income, including the gain.
| Filing status | 2025: 0% up to | 2025: 15% up to | 2026: 0% up to | 2026: 15% up to |
|---|---|---|---|---|
| Single | $48,350 | $533,400 | $49,450 | $545,500 |
| Married filing jointly | $96,700 | $600,050 | $98,900 | $613,700 |
| Married filing separately | $48,350 | $300,000 | $49,450 | $306,850 |
| Head of household | $64,750 | $566,700 | $66,200 | $579,600 |
Short-term gains (held one year or less) are taxed at ordinary rates instead. NIIT adds 3.8% above the statutory MAGI thresholds. State tax is separate and estimated only from a rate you enter.
Frequently Asked Questions
How does this differ from a flat capital-gains calculator?
A flat calculator multiplies the gain by a single rate. This planner computes your federal tax with and without the sale and attributes the difference to the sale, so it captures bracket stacking, the 0%/15%/20% long-term bands and the 3.8% NIIT that a single rate misses.
When is a gain long-term?
A gain is long-term when the asset is held more than one year. The holding period begins the day after your purchase trade date, so the planner shows the first date on which a sale would qualify for long-term treatment.
What is the Net Investment Income Tax (NIIT)?
NIIT is an additional 3.8% on the lesser of your net investment income and the amount your MAGI exceeds a statutory threshold ($200,000 single/head of household, $250,000 married filing jointly, $125,000 married filing separately). It can be zero even above the threshold if you have little net investment income.
How are losses and carryovers handled?
Short-term and long-term gains and losses are netted (short against short, long against long, then across), including any carryovers you enter. A net capital loss offsets ordinary income up to $3,000 ($1,500 if married filing separately); the rest carries forward.
Is state tax included?
Only as an optional rough estimate: your entered rate applied to a positive gain, shown separately. This is not a state-tax engine and does not implement any state\u2019s specific rules.
What does the tax-lot comparison do?
If you hold multiple lots, it compares FIFO, LIFO, HIFO, losses-first and long-term-first selection for a target number of shares or proceeds, and reports the least-cost strategy among those computed. It does not claim a globally optimal answer and does not recommend specific replacement securities.
Is this tax advice?
No. It is an educational estimate calculated from the values you enter, for US individuals with ordinary capital assets. Consult a qualified tax professional before acting, and confirm figures against the current IRS guidance.
Evidence, sources and editorial review
Capital Gains Sale Planner: Sell Now, Wait, or Choose Different Tax Lots groups its evidence and methodology review here so sources, assumptions and responsibility can be checked together.
Methodology & formula
Federal Capital Gains Sale Planner (baseline vs after-sale). incrementalRegularFederalTax = afterSaleRegularFederalTax − baselineRegularFederalTax; incrementalNiit = afterSaleNiit − baselineNiit; total = incremental regular + incremental NIIT + optional state estimate
Regular federal tax uses the ordinary brackets and the Qualified Dividends & Capital Gain worksheet (0%/15%/20% stacked above ordinary taxable income). NIIT = 3.8% × min(net investment income, MAGI over the statutory threshold). Long-term = held more than one year. State is an optional rough estimate = max(0, gain) × entered %.
This planner estimates the federal tax ATTRIBUTED TO A PROPOSED SALE as the difference between a baseline scenario (your year without the sale) and an after-sale scenario — not a single rate multiplied by the gain. It classifies the holding period as short-term or long-term (held more than one year), nets short and long-term gains and losses with any carryovers, applies the ordinary-income brackets and the Qualified Dividends and Capital Gain Tax Worksheet (0%/15%/20% stacked above ordinary taxable income) for tax years 2025 and 2026, and adds the 3.8% Net Investment Income Tax as the lesser of net investment income and MAGI over the statutory threshold. It also models waiting for long-term treatment, a tax-only break-even future price, tax-loss harvesting headroom, remaining 0% long-term band, and a tax-lot comparison across FIFO, LIFO, HIFO, losses-first and long-term-first strategies. State tax is an optional rough estimate from a rate you enter, shown separately. Scope: US individuals with ordinary capital assets (stocks, ETFs, funds, bonds, crypto). It is an educational estimate, not tax advice, a filing, or a guaranteed figure.
Reviewed according to the CalcDomain Editorial Policy & Calculator Methodology. We document formulas, edge cases, sources, update dates, and correction paths for calculator pages.
Updated · engine federal-capital-gains-1
References & Authoritative Sources
- Internal Revenue Service (IRS) — Topic no. 409, Capital gains and losses · consulted July 29, 2026 · Holding period, long-term vs short-term, capital-loss limits.
- Internal Revenue Service (IRS) — Publication 550, Investment Income and Expenses · consulted July 29, 2026 · Netting, carryovers and wash-sale rules.
- Internal Revenue Service (IRS) — Schedule D (Form 1040) instructions · consulted July 29, 2026 · Capital gain and loss reporting and the tax worksheet.
- Internal Revenue Service (IRS) — Net Investment Income Tax (NIIT) · consulted July 29, 2026 · 3.8% NIIT and MAGI thresholds (IRC \u00a71411).
- Internal Revenue Service (IRS) — Rev. Proc. 2024-40 and Rev. Proc. 2025-32 · consulted July 29, 2026 · 2025 and 2026 inflation-adjusted brackets and long-term breakpoints.
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Update history
| Date | Version | Change |
|---|---|---|
| 2026-07-04 | 1.0 | Original flat capital gains calculator (realized gain times an entered rate). |
| 2026-07-29 | 2.0 | Rebuilt as a Capital Gains Sale Planner: baseline vs after-sale federal tax, holding-period classification, ST/LT netting with carryovers, NIIT, wait-until-long-term, tax-only break-even price, loss harvesting, 0% band headroom, and a tax-lot comparison engine. |