Short-Term and Long-Term Classification
The Internal Revenue Code classifies realised gains by holding period. A position held for one year or less, then sold at a profit, produces a short-term capital gain, taxed at the holder’s ordinary income rate — the same schedule that applies to wages, ranging from 10% to 37% federal in the 2024 brackets. A position held for more than one year produces a long-term capital gain, taxed at a preferential schedule of 0%, 15%, or 20% federal, with the marginal rate determined by total taxable income.
| Holding Period | Classification | Federal Rate (2024) |
|---|---|---|
| One year or less | Short-term capital gain | Ordinary income (10–37%) |
| More than one year | Long-term capital gain | Preferential (0%, 15%, or 20%) |
The arithmetic gap is the central object of capital-gains planning. A trader in the 32% federal bracket who realises $50,000 in short-term gains owes $16,000 in federal tax. The same $50,000, qualified as long-term at the 15% rate, produces $7,500. The holding period alone, on identical economic profit, accounts for an $8,500 federal swing — before any state liability is added. For day traders and swing traders whose realised profit is, by construction of the strategy, almost entirely short-term, the maximum applicable rate is the practical default.
Calculation and Cost Basis
Capital Gain = Sale Price − Cost Basis
The cost basis is the amount paid for the security, including commissions and any other acquisition cost permitted under the regulations. A purchase of 100 shares at $25, plus a $10 commission, produces a basis of $2,510. A sale at $35 net of a $10 commission produces proceeds of $3,490. The realised gain is $3,490 − $2,510, or $980. The figure is then characterised as short-term or long-term according to the holding period.
When the same security has been acquired across multiple lots at different prices, the trader has, in most cases, a choice of which lot is being sold — and the choice is consequential. Two methods are in common use:
- FIFO (First In, First Out): the default at most retail brokers absent a specific instruction. The oldest lot is treated as sold first. Where the oldest shares are also the lowest-cost shares, FIFO maximises the realised gain and accelerates the tax liability.
- Specific identification: the trader designates the precise lot at the time of the sale. The designation must be communicated to the broker before settlement to be respected by the IRS. Specific identification permits the trader to choose, within the inventory of held lots, whether the realised result is a gain or a loss, and whether the holding period qualifies as short-term or long-term.
The position-by-position character of the choice is closer to chess than to most things in finance: the move under consideration is not the trade in isolation but the structure of the inventory left behind, including which lots remain available for harvesting in later quarters. Selling the wrong lot in March can foreclose a useful tax option in December.
Capital Losses, Offsets, and Carry-Forward
Realised capital losses offset realised capital gains dollar for dollar. A trader closing the year with $20,000 in realised gains and $15,000 in realised losses owes federal capital-gains tax only on the net $5,000.
Where losses exceed gains, the IRS permits a deduction of up to $3,000 of net capital losses per year against ordinary income — wages, interest, and similar. Net losses beyond that ceiling carry forward indefinitely against future capital gains, with the same $3,000 annual application against ordinary income each subsequent year until the carry-forward is exhausted. A trader closing the year with $50,000 in realised losses and $10,000 in realised gains has a $40,000 net loss: $3,000 deducted in the current year, $37,000 carried forward.
Tax-Loss Harvesting
Tax-loss harvesting is the deliberate sale of unrealised losing positions, before year-end, in order to realise losses that offset gains realised earlier in the same year. It is among the most economically substantial legal mechanisms available for reducing the tax owed on a profitable trading year.
The mechanic is straightforward in principle. A trader with $30,000 in realised year-to-date gains holds two open positions at a loss: position A is down $8,000, position B is down $5,000. Closing both before year-end realises $13,000 in losses, reducing the net taxable gain to $17,000. At a 32% marginal rate, the harvested losses save $4,160 in federal tax. The economic loss on positions A and B was already incurred at the moment the price moved against them; harvesting is the act of converting that already-suffered economic loss into a usable tax deduction.
Market exposure does not need to be sacrificed to capture the loss. A losing concentrated position in a technology name can be replaced with a sector ETF that holds the same name as one component among many. A losing energy stock can be replaced with a different operator in the same sector. The portfolio’s broad risk profile is preserved; the tax loss is captured.
The Wash Sale Rule
The wash sale rule blocks the most direct version of the trade. If a security is sold at a loss and a substantially identical security is purchased within 30 days before or after the sale, the loss is disallowed for current-year tax purposes. The disallowed amount is instead added to the cost basis of the replacement lot. The deduction is deferred to the eventual sale of the replacement lot, not eliminated.
Example: XYZ is sold on December 15 at a $5,000 loss. On January 5, twenty-one days later, XYZ is purchased again. The $5,000 loss is disallowed for the year of sale. The new lot’s cost basis is raised by $5,000, recovering the loss when the replacement is eventually sold — in a future tax year, with whatever discount rate the trader implicitly assigns to the deferral.
The practical discipline that follows is narrow:
- Wait at least 31 days before repurchasing the same security after a loss-realising sale.
- Replace the position with one that is similar but not substantially identical — a different company in the same sector, or a sector ETF in place of a single stock.
- Maintain a running wash-sale log throughout the year. The rule is straightforward to trigger inadvertently, particularly across multiple accounts and across spouses, where the IRS aggregates activity into a single ledger.
Strategies for Active Traders
Several specific practices follow from the structure described above.
Concentrate active trading inside tax-advantaged accounts where possible. Realised gains inside a Roth IRA are not taxed at all on qualified distribution. Short-term gains that would be taxed at 37% in a taxable account are taxed at 0% inside the Roth. The annual contribution limit is modest — $7,000 for most filers under 50 in 2024 — but the compounding of tax-free realised gains over decades of active trading is, on the available arithmetic, substantial.
Hold profitable positions through the twelve-month threshold where the underlying thesis remains intact. A swing position approaching the one-year mark is often worth holding for the additional weeks required to convert the gain from short-term to long-term, provided the conviction in the position has not deteriorated for non-tax reasons. Holding a deteriorating thesis purely for the rate is the inverse error and is generally costlier than the tax saved.
Harvest losses in December. The last two weeks of the calendar year are the standard window for reviewing realised gains against the inventory of open losing positions and selecting which to close. The wash sale rule is the binding constraint on the timing — the replacement transaction has to clear the 30-day window on either side.
Maintain independent trade records. The 1099-B issued by a broker may contain errors, particularly in wash-sale reporting and in cost basis on securities transferred between brokers. Reconciling broker reports against an independent trade log is standard practice for any account running meaningful volume. Tax software designed for active traders handles the reconciliation directly and produces the Form 8949 detail in the format the IRS expects.
Consider trader tax status under Section 475(f) only with professional guidance. Traders who meet the IRS thresholds for trade frequency, holding period, and intent may elect mark-to-market accounting. The election eliminates the wash sale rule, removes the $3,000 ceiling on net-loss deduction against ordinary income, and treats all realised gains and losses as ordinary income rather than capital. The election is consequential, narrowly available, and irrevocable for the tax year in which it is made. It should not be elected without consultation with a tax professional familiar with the trader-status case law.
This last point deserves a sharper statement than the surrounding hedging suggests. A retail trader who self-elects 475(f) without first establishing, through trade frequency and recordkeeping, that the IRS will respect the election is in a poor position if the return is examined. The right sequence is professional review first, election second, not the reverse.
State-Level Tax
Capital gains are taxed at the state level in most states. State rates range from 0% in the nine states without an income tax on wages and capital gains (Texas, Florida, Nevada, Tennessee, Washington, South Dakota, Wyoming, Alaska, and New Hampshire on wages) to above 13% in California at the top bracket. For a California resident in the 37% federal bracket, the combined federal-and-state marginal rate on short-term gains approaches 50%. Approximately half of each marginal short-term dollar is owed to the federal and state treasuries before the trader receives net proceeds. The tax plan is not adjacent to the trading business; it is a structural component of its economics.
The Discipline of Looking Past the Pre-Tax Number
Active trading is, in the end, a long-distance event rather than a sprint. The trader who optimises gross P&L without reference to the tax line will, over a decade, deliver after-tax compounding measurably below what the same gross record would produce under disciplined holding-period management, lot selection, and December-window loss harvesting. When I worked in equity research, the senior analyst who reviewed our personal-account trading kept a single laminated card on his desk: gross is vanity, after-tax is the result. The framing has held up.
What this article does not do is substitute for tax advice on a specific return. The categorisation of a particular trade, the substantially-identical determination on a particular pair of securities, and the eligibility for trader tax status under Section 475(f) are determinations that depend on facts specific to the account and on case law a generalist treatment cannot fully cover. The framework above is sufficient to organise the planning; the final reconciliation belongs with a qualified preparer.
See also: IRA · 401(k) · How to Open a Brokerage Account · Day Trading · Budgeting
