Tax-loss harvesting works by selling a position trading below its cost basis, using the realized loss to offset capital gains and up to $3,000 of ordinary income per year under Internal Revenue Service rules, and redeploying the proceeds to maintain market exposure. The strategy's central constraint is the wash sale rule of Section 1091: a loss is disallowed if substantially identical securities are bought within thirty days before or after the sale — a sixty-one-day window. NewsJay publishes information and education, not tax or investment advice; confirm specifics with IRS publications or a qualified professional.
How does the mechanics of harvesting work?
Realized capital losses first offset realized gains of the same type — short against short, long against long — then net across types, and the remainder offsets up to $3,000 of ordinary income in the tax year, with any excess carried forward to future years indefinitely. An investor with $8,000 of harvested long-term losses and $5,000 of realized gains pays tax on zero net gains and deducts the remaining $3,000 against salary, carrying $0 forward in this example — the arithmetic is simple, and brokerage 1099 forms track it automatically.
What is the wash sale rule, precisely?
The rule disallows a loss when the investor acquires substantially identical securities within a window spanning thirty days before the sale through thirty days after — sixty-one days in total, per the IRS's Publication 550 guidance. It applies per person across accounts, including IRAs: buying the replacement inside a retirement account disallows the loss permanently, because the basis adjustment that normally defers the disallowed loss cannot follow into an IRA, per the IRS's 2008 ruling. Dividend reinvestment plans are the classic accidental trigger — an automatic reinvestment two weeks after harvesting the same fund re-purchases within the window and voids that slice of the loss.
| Step | Action | Rule to respect |
|---|---|---|
| 1 | Sell the loss position | Loss must be realized, not just on paper |
| 2 | Buy a similar, not identical, fund | Not substantially identical — e.g., a different index |
| 3 | Hold the replacement 31+ days | Before switching back to the original |
| 4 | Report per the 1099-B | Brokerages flag wash sales automatically |
How is exposure maintained during the window?
The point of harvesting is capturing the tax loss without leaving the market. The standard method replaces the sold fund with a similar but not substantially identical one — one total-market fund for another tracking a different broad index, or a large-cap fund paired with a different large-cap index during the holding period. Swapping between two funds tracking the same index is the gray zone the rule's language does not fully resolve; using genuinely different indexes keeps the practice clearly onside. After thirty-one days, the investor may switch back if the original fund still serves the plan.
What are the real costs and limits?
Harvesting defers tax rather than eliminating it — the replacement carries a lower basis, so future gains will be larger, and the benefit compounds only if tax rates fall or the deferral stretches across years. Transaction costs and bid-ask spreads eat small harvests. The $3,000 ordinary-income offset is annual and modest against a working career's salary. And harvesting in a falling market that recovers can leave the replacement higher-priced than the sale, converting a paper loss into a smaller realized benefit than it appeared. None of this makes the tool weak; it makes it arithmetic, best used deliberately at scale rather than reflexively.
When does harvesting make the most sense?
High-income years with large realized gains, volatile markets that hand out losses to diversified portfolios, and taxable accounts big enough that the mechanics justify attention. Tax-advantaged accounts gain nothing from harvesting — losses inside an IRA are never deductible. The disciplined annual routine pairs naturally with rebalancing checks in the fourth quarter.
What does a disciplined harvesting year look like?
A practical annual routine fits one sitting in the fourth quarter, or opportunistically after sharp selloffs. List every taxable position below basis, ranked by dollar loss; check each against the wash sale window for planned purchases and automatic reinvestments; harvest losses large enough to exceed transaction costs by a wide margin; replace sold exposure with a similar fund tracking a different index; and log the trades, the replacement funds, and the switch-back dates — thirty-one days out — in the same file as the basis records. The routine ends with the math: gains realized this year, losses available, the $3,000 ordinary-income slice, and the carryforward that rolls into next year's plan. What the routine never includes is selling anything the portfolio should keep — harvesting is a tax transaction, not an investment decision, and the replacement fund exists so the market exposure never blinks.
How do robo-advisors and managed accounts do it?
Automated platforms run the same playbook continuously rather than annually: software monitors lots daily, harvests whenever losses clear thresholds, and swaps among a family of similar index funds — the mechanics this guide describes, executed at scale with the wash sale bookkeeping handled by the system. The service is worth its fee for some investors and redundant for others: a simple three-fund portfolio in one account needs an hour a year to harvest manually, while multi-account households with many lots get real value from automation. The decision rule is the same one every fee question gets — know what the service does, compare it to the DIY hour, and pay only for the difference.
What is the one-sentence summary?
Harvest losses into similar-but-different funds, respect the sixty-one-day window everywhere including retirement accounts and reinvestment plans, and treat the whole exercise as a tax calendar item with a basis ledger — because the losses that count are the ones the paperwork survives.
FAQ
How much loss can I deduct per year?
Net capital losses offset unlimited realized gains, then up to $3,000 of ordinary income per year, with the remainder carried forward indefinitely. Married couples filing separately get $1,500 each, per IRS rules.
What counts as substantially identical?
The same security, clearly; the same fund under two wrappers, yes; two funds tracking different indexes, no. Two funds tracking the same index occupy unresolved ground — practitioners differ, and the conservative course chooses different indexes.
Does my brokerage handle wash sale tracking?
Brokerages report wash sales within the same account on Form 1099-B automatically. Cross-account and cross-institution purchases remain the investor's own responsibility to track, which is where most disallowed-loss surprises originate.
Should I harvest losses in my IRA?
There is nothing to harvest — losses inside tax-advantaged accounts have no deductibility to begin with, and purchases there can void losses harvested in taxable accounts. Harvesting belongs exclusively to taxable accounts.
For more context, read What Compounding Actually Looks Like in an Index Fund.
For more context, read dividend reinvestment compounding.
For more context, read How Often Should You Check Your Portfolio.
