What Is a Trader? IRS Definition, Section 475(f), and Deductions

The IRS definition of a trader in securities is narrow: you qualify only if you seek profit from daily market movements, your trading is substantial in both volume and dollar amount, and you trade with continuity and regularity throughout the tax year.¹ All three conditions have to be met. Meeting them turns your trading into a business for tax purposes, which unlocks deductions and elections that ordinary investors cannot use. Falling short leaves you classified as an investor, with capital loss limits and non-deductible trading costs.

The Three Tests You Have to Meet

The IRS lists three requirements for trader status, and they are cumulative rather than alternative:

You must seek to profit from daily market movements in the prices of securities, not from dividends, interest, or long-term capital appreciation.
Your activity must be substantial.
You must carry on the activity with continuity and regularity.

The third test is the one that catches most people. Trading heavily for a month or two and then going quiet for the rest of the year is exactly the pattern the IRS points to when denying trader status. In Paoli v. Commissioner, the Tax Court found that a single month of concentrated trading did not establish the year-round consistency required, even though the taxpayer said he spent four hours a day on market activity.¹

What the IRS Actually Weighs

Because “substantial” and “continuous” are not defined by a bright-line number, the IRS looks at four factors together when deciding whether trading rises to the level of a business:

Typical holding periods. Short holding periods, measured in days or weeks, support trader status. Holding for months cuts against it.
The frequency and dollar amount of trades during the year. Dozens of trades per week is more persuasive than a handful per month.
The extent to which you pursue the activity to produce income for a livelihood, rather than as a side activity to a full-time job.
The amount of time you devote to the activity each day.

No single factor is decisive, and the IRS has never published a threshold number of trades that automatically qualifies you.¹ The pattern that wins is high frequency, short holds, meaningful hours each day, and activity spread across the whole year.

What Happens If You Don’t Qualify

If your activity doesn’t meet all three tests, the IRS treats you as an investor. That has two hard consequences. Your trading expenses are not deductible as business costs. And your losses are capital losses, so you can only deduct up to $3,000 in net capital losses against ordinary income each year, or $1,500 if you’re married filing separately, with the rest carried forward.² An $80,000 losing year would take more than 25 years to fully deduct at that rate. Brokerage commissions and transaction costs get capitalized into the basis of each security rather than expensed.¹

The Mark-to-Market Election Under Section 475(f)

The single biggest tax benefit of qualifying is the ability to elect mark-to-market accounting under Section 475(f).³ Without the election, your trading gains and losses remain capital in character, and the $3,000 annual loss cap applies. With the election, all trading gains and losses become ordinary, the cap disappears entirely, and a bad year is fully deductible against your other income. Open positions are treated as sold at fair market value on the last business day of the year, which also simplifies basis tracking.¹

The Deadline Is Unforgiving

You must file the election by the due date, without extensions, of the return for the year before the election takes effect. Mark-to-market treatment for 2026 required the election to be attached to the 2025 return filed by April 2026. There is no retroactive election after you see how the year went.¹

The election itself is a statement attached to your prior-year return, or to an extension request, that identifies the election as being made under Section 475(f), states the first tax year to which it applies, and specifies the trade or business it covers. A new taxpayer who was not required to file a prior-year return can instead place the statement in books and records within two months and 15 days after the start of the election year, then attach it to that year’s return.¹

Carving Out Long-Term Holdings

The election does not have to sweep in every security you own. Positions you hold as long-term investments can stay outside mark-to-market, but you have to identify them in your records before the close of the day you acquire them.³ Miss that identification and the position gets pulled into mark-to-market at year-end.

Wash Sale Relief for Electing Traders

The wash sale rule disallows a loss on a security if you buy a substantially identical security within 30 days before or after the sale. The disallowed loss is added to the basis of the replacement, so it’s deferred rather than lost, but for a trader who cycles in and out of the same stocks, that deferral can stretch indefinitely and turn record-keeping into a full-time chore.⁴

Traders who have made the Section 475(f) election are exempt from the wash sale rule. Because everything is marked to market at year-end and treated as ordinary, the rationale for disallowance falls away.¹ For a high-frequency stock trader, this exemption alone can justify the election.

One boundary worth noting: the wash sale rule under IRC Section 1091 applies only to stocks and securities. As of 2026, the IRS classifies digital assets as property rather than securities, so cryptocurrency traders can sell at a loss and immediately repurchase without triggering a wash sale. Legislation has been proposed to close the gap, but nothing has been enacted.

Business Deductions on Schedule C

Qualifying as a trader means the IRS treats your trading as a business, and ordinary business expenses are deductible on Schedule C. Common categories include:

Home office costs, if you have a space used exclusively for the trading business. You can calculate actual expenses on Form 8829 or use the simplified method at $5 per square foot up to 300 square feet.
Computers, monitors, trading platforms, and market data subscriptions. For larger equipment purchases, Section 179 allows expensing up to $2,560,000 in qualifying property in 2026 rather than depreciating it over years, though that ceiling is well beyond what any individual trader spends.
Charting software, market data services, and trading-related courses.
Accounting and tax preparation fees tied to the trading business.

These deductions reduce adjusted gross income, which can carry through to other tax calculations.¹

What Trader Status Does Not Give You

Three things surprise people who assume “trade or business” treatment behaves like any other self-employment.

First, gains and losses from selling securities are not subject to self-employment tax, even though the activity qualifies as a trade or business.¹ That saves the 15.3% Social Security and Medicare tax, but it creates the second problem: because trading income isn’t earned income for self-employment tax purposes, it doesn’t support contributions to a Solo 401(k) or SEP IRA. A trader whose entire livelihood is market income has no way to make tax-advantaged retirement contributions from that income without a separate source of earned income.

Third, the 20% qualified business income deduction under Section 199A is off the table. Trading in securities is specifically listed as a specified service trade or business that does not qualify for QBI treatment.⁵ No matter how much your trading business earns, that deduction is not available on trading profits.

1
Internal Revenue Service. Topic No. 429, Traders in Securities
2
Internal Revenue Service. Topic No. 409, Capital Gains and Losses
3
Office of the Law Revision Counsel. 26 U.S. Code 475 – Mark to Market Accounting Method for Dealers in Securities
4
Internal Revenue Service. Publication 550, Investment Income and Expenses
5
Office of the Law Revision Counsel. 26 U.S. Code 199A – Qualified Business Income