Tax-Loss Harvesting Calculator 2026: Wash-Sale Check, $3,000 Rule and 0% Gain Harvesting
Full Schedule D netting — short vs long term, the $3,000 loss limit, character-preserving carryforward, NIIT, and your 0% bracket headroom.
Enter this year's gains, losses, and carryovers and the calculator runs the exact Schedule D sequence: same-character netting, cross-character offset, the $3,000 ordinary-income deduction ($1,500 married filing separately), and the character-split carryforward to next year — then prices it all with 2026 federal brackets, the long-term capital-gains stack, and the 3.8% net investment income tax.
How much tax does harvesting a loss save in 2026?
A harvested loss saves the tax on whatever it offsets: short-term gains and ordinary income save the most, long-term gains less, and gains already in the 0% band nothing. A single 66-year-old in California with $30,000 of Social Security, $40,000 of IRA withdrawals and a $25,000 long-term gain who sells $10,000 of losing positions pays $1,662 less federal tax (16.6% of the loss, above the 15% rate because the gain was pulling Social Security into tax) and $600 less California tax. The other year-end move is the reverse: a couple, 62 and 60, with a $50,000 pension can realize $81,100 of long-term gain at 0% federal ($0 of federal tax), though California still taxes it: $3,599. A sale counts for 2026 only if it trades by December 31, and buying the same security back within 30 days before or after a loss sale disallows the loss (IRC §1211; wash sales: IRC §1091, checker below).
| Key number | 2026 |
|---|---|
| $10,000 of long-term losses: federal tax cut (Rev. Proc. 2025-32) | $1,662 |
| … California tax cut (CA rules) | $600 |
| … federal cut per dollar of loss (Pub. 915) | 16.6% |
| $10,000 of short-term losses (on $90,000 of wages): federal cut | $2,200 |
| … California cut | $930 |
| Long-term gain at 0% federal (couple, $50,000 pension) | $81,100 |
| … federal tax on it | $0 |
| … California tax on it (CA rules) | $3,599 |
An estimate from QuantCalc’s open tax engine (federal 2.0.0, state 1.12.0) for the 2026 tax year. Not tax advice: your return depends on facts this page does not ask about, so check a move with your tax preparer or custodian before acting. How the engine computes each line, with its official source: federal, state.
Netting summary
Federal tax breakdown
| Component | Amount | Notes |
|---|---|---|
| Federal ordinary income tax | — | |
| Federal long-term capital gains tax | — | |
| Net investment income tax (3.8%) | — | |
| State tax on capital items PRO | 🔒 PRO | Unlock to see the state layer for your selection |
| Total | — |
Next decision: Harvested losses change your bracket headroom — size a Roth conversion into the freed-up bracket →
0% bracket headroom
How much more long-term gain fits at a 0% federal rate this year, on top of everything entered above.
NIIT threshold check
The 3.8% net investment income tax starts at a statutory MAGI threshold that never inflates.
Model your whole retirement, not just this year
This page prices one tax year. The full QuantCalc planner runs a Monte Carlo (100 paths free, up to 10,000 with PRO) over your entire retirement — withdrawals, taxes, Roth conversions, and sequence risk together.
Model your whole retirement, not just this year — free Monte Carlo planner →Frequently Asked Questions
How does tax-loss harvesting work in 2026?
Tax-loss harvesting means selling investments that have fallen below your cost basis to realize a capital loss on purpose. On Schedule D, losses first offset gains of the same character — short-term against short-term, long-term against long-term — and any remainder crosses over to offset the other character. Up to $3,000 of a leftover net loss ($1,500 married filing separately) then reduces ordinary income, and everything beyond that carries forward to future years. Because short-term gains are taxed at ordinary rates up to 37% while long-term gains top out at 20% plus the 3.8% net investment income tax, a harvested loss is worth the most when it lands on short-term gains or ordinary income.
What is the $3,000 capital loss limit ($1,500 married filing separately)?
After all gains and losses are netted, a net capital loss can offset at most $3,000 of ordinary income per year — $1,500 if married filing separately (IRC §1211(b)). The limit is per return, not per person, and it is not indexed to inflation. Losses above the limit are not wasted: they carry forward indefinitely, and under the IRS carryover worksheet a loss is only treated as used up to the extent your taxable income was positive before the capital-loss deduction.
What is the wash-sale rule (61-day window, basis adjustment)?
If you sell a security at a loss and buy the same or a substantially identical security within 30 days before or 30 days after the sale — a 61-day window centered on the sale date — the loss is disallowed under IRC §1091. For a repurchase in a taxable account the disallowed loss is added to the basis of the replacement shares and the original holding period tacks on, so the loss is deferred rather than destroyed. A repurchase inside an IRA permanently disallows that portion of the loss with no basis adjustment (Rev. Rul. 2008-5). The rule only applies to losses — winners can be repurchased immediately.
Do losses carry forward and do they keep their short/long-term character?
Yes. Unused capital losses carry forward indefinitely for individuals and retain their character under IRC §1212(b): a short-term carryover enters next year's short-term netting and a long-term carryover enters the long-term netting. Character matters because short-term gains are taxed at ordinary rates, so a short-term carryover that absorbs short-term gains saves more per dollar than a long-term one. When the $3,000 ordinary-income offset is consumed, short-term loss is treated as used before long-term.
What is the 0% capital-gains bracket and who can use it?
For 2026, long-term capital gains are taxed at 0% federal to the extent taxable income stays under $49,450 (single), $98,900 (married filing jointly), or $66,200 (head of household). Because the standard deduction ($16,100 single / $32,200 joint) comes off first, a married couple with no other income could realize roughly $131,100 of long-term gains at a 0% federal rate. Low-income years — early retirement, sabbaticals, between jobs — are the classic window, and gain harvesting in those years resets basis upward for free. Note that 0%-rate gains still count toward state tax, the net investment income tax threshold, and ACA/IRMAA income tests.
Does harvesting always save money?
No. If the gains a harvest offsets would have been taxed at 0% anyway, the harvest saves nothing today while still lowering your cost basis — so you may simply owe more tax when you eventually sell. Whether a harvest pays off depends on the rate you save now versus the rate you expect on the deferred gain later, and on how long the deferral lasts. The harvest analyzer on this page computes the net present value: tax saved now, minus the discounted future cost of the reduced basis, with a break-even future rate — and treats the future cost as zero if the position will get a step-up in basis or be donated.
How much tax does harvesting a loss save in 2026?
It depends on what the loss offsets. A single 66-year-old in California with $30,000 of Social Security, $40,000 of IRA withdrawals and a $25,000 long-term gain who sells $10,000 of losing positions cuts federal tax by $1,662 and California tax by $600, because the gain was also pulling Social Security into tax. Against $10,000 of short-term gains on $90,000 of wages, the cut is $2,200 federal. A loss that offsets gains taxed at 0% saves nothing now, and a sale counts for 2026 only if it trades by December 31.