Planning tool · For founders & business owners
What is systematic loss harvesting worth before your exit?
An owner heading toward a sale usually carries two tax problems at once: the gain on the business itself, and the gains that keep arriving as concentrated positions and proceeds get diversified afterward. Systematic tax-loss harvesting works on both. A long-only account harvests the losses that ordinary market movement creates; a long/short extension (130/30 or 200/100) adds a short book that generates materially more harvestable loss per dollar invested, at higher cost and complexity.
This calculator models what each approach could realize in capital losses over ten years, and what those losses would be worth against your gains at your actual 2026 federal and state marginal rates. It exists to size the opportunity, not to recommend a strategy; that conversation depends on facts a calculator cannot hold.
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Capital gains you could offset
Cumulative capital losses harvested, by year and strategy. Each dollar of harvested loss can absorb a dollar of realized capital gain.
| Year | Long only | 130/30 | 200/100 |
|---|
Tax dollars those losses could save
Cumulative tax savings at your blended marginal rate on the gains each strategy offsets, assuming you realize at least the gains entered above each year.
| Year | Long only | 130/30 | 200/100 |
|---|
Assumptions and limitations. Loss-harvesting rates are derived from published third-party simulations of tax-managed strategies (averages across 25 simulated portfolios over ten-year horizons, with tax savings reinvested), fitted so each strategy’s ten-year cumulative losses equal the published endpoints of 50% (long only), 145% (130/30), and 433% (200/100) of contributed capital. Simulated results are hypothetical: they do not reflect actual trading, and actual harvesting depends entirely on market behavior that no one controls. Real results will differ, possibly by a lot, and losses harvested in any single year can be far below these averages, including zero.
Additions are modeled as arriving monthly and each dollar harvests on its own schedule from its arrival date. Tax rates use the 2026 federal schedules (Rev. Proc. 2025-32), the 3.8% net investment income tax, and each state’s 2026 rates including capital-gains exclusions, preferential caps, and surtaxes; short-term losses are assumed to be 0% of the total for long-only, 35% for 130/30, and 50% for 200/100, valued at ordinary rates. The savings table assumes you actually realize at least the entered gains every year; a harvested loss with no gain to absorb carries forward and is worth nothing until used. Not modeled: strategy costs (management fees, financing and borrow costs, tracking error, all of which are materially higher for long/short extensions and reduce these figures), the federal deductibility of state taxes, local income taxes, the alternative minimum tax, the $3,000 ordinary-income offset, and loss-carryforward timing.
This tool is general education, not individual tax, legal, or investment advice, and no outcome shown is promised or guaranteed. Whether any of these strategies fits your situation depends on your holdings, cost basis, liquidity, and risk tolerance. Aspirean Wealth, LLC is an SEC-registered investment adviser; registration does not imply a certain level of skill or training.
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Numbers this size deserve a second set of eyes.
If the ten-year figures are material to your exit, the right next step is a conversation about whether the strategy fits, not a bigger spreadsheet.
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