Section 475 Mark-to-Market Election for 2027: Deadline, Statement, and Form 3115

For active traders, the Section 475(f) mark-to-market election can materially change how securities trading gains and losses are reported. When the election is timely and valid, trading securities are generally reported with ordinary gain or loss treatment, and the wash sale and capital loss limitation rules generally do not apply to the elected trading activity. When the facts or timing are wrong, the result can be expensive.

Trader Tax Status: The Prerequisite

Before discussing the 475(f) election, the taxpayer must qualify as a trader in securities rather than an investor. IRS Topic 429 focuses on whether the taxpayer seeks profit from daily market movements, whether the activity is substantial, and whether it is carried on with continuity and regularity.

The practical review looks at holding periods, frequency, dollar amount of trades, time devoted to trading, and whether investment positions are clearly separated from trading positions. There is no single trade-count shortcut that replaces the facts.

Documentation matters. Trading logs, broker exports, a trading calendar, account separation, and a clearly supported business narrative all strengthen the return position.

What the 475(f) Election Does

Once a qualifying trader makes a timely and valid election, securities subject to the election are marked to market. The mechanics:

• Open trading positions are generally marked to fair market value at year-end.

• Gains and losses from elected trading securities are generally ordinary, not capital, and are generally reported on Part II of Form 4797.

• Wash sale rules under Section 1091 generally do not apply to securities subject to the mark-to-market method.

• The capital loss limitation generally does not apply to elected trading securities.

• Securities held for investment should be identified separately and kept out of the trading activity records.

The Trade-Off

The trade-off is real. Ordinary gain or loss treatment can help a trader with significant losses or wash sale exposure, but it can be unfavorable if the activity includes positions that would otherwise receive long-term capital gain treatment. IRS Topic 429 also notes that gains and losses from selling securities as a trader are not subject to self-employment tax, so retirement plan and entity planning should be modeled separately rather than assumed.

What Is the 2027 Mark-to-Market Election Deadline?

For an existing taxpayer, the 475(f) election must be filed by the unextended due date of the prior year's return. For a calendar-year individual electing Section 475 for tax year 2027, that generally means filing the election statement by April 15, 2027, the due date of the 2026 return without extensions. The statement is attached to the timely filed 2026 return or to a timely extension request for that return; extending the 2026 return does not extend the election deadline. Form 3115 is generally filed later, with the 2027 return, because 2027 is the year of change.

For a new taxpayer that was not required to file a 2026 return, IRS Topic 429 describes a separate timing rule: place the election statement in the books and records no later than 2 months and 15 days after the first day of the election year, which for a calendar-year 2027 election is measured from January 1, 2027. A copy must also be attached to the 2027 tax return.

Late elections are generally not allowed. The April 15, 2026 deadline for 2026 elections has passed, so an existing calendar-year individual who did not file a timely 2026 election generally must wait and elect for 2027. That is why mark-to-market election consulting should happen before the deadline, not after a losing year is already known. For the IRS framework, see IRS Topic 429.

Election Statement and Form 3115: Separate Steps

1. Confirm eligibility: The election does not establish trader tax status. Document the trading activity first.
2. Prepare the statement: Identify Section 475(f), the first effective tax year, and the trading business covered. Follow the election deadline above.
3. Complete the accounting change: A trader changing an existing method generally attaches Form 3115 (designated change number 64) to the timely filed return for the election year, including extensions (for a 2027 election, the 2027 return), under Revenue Procedure 2025-23, section 24.01, and files a signed duplicate copy with the IRS no later than the date the original is filed, as the Form 3115 instructions require. This is separate from the timely election statement.

Missed the statement deadline? Filing Form 3115 alone does not cure a late election. A taxpayer generally must elect for a following year; unusual relief questions require a separate facts-and-procedure review.

Records to Bring to a Section 475 Review

• Broker transaction exports and a calendar showing when and how regularly you traded.
• Year-end positions, cost records, and fair-value support for each trading account.
• Records identifying investment holdings separately from trading positions.
• The election statement, filing or delivery evidence, prior return or extension, and any earlier Forms 3115.

For example, a trader using two brokers should reconcile both exports before reviewing year-end positions. A missing account can distort the accounting review even when the election statement was filed on time.

Entity and Record Structure Matters

Entity planning should follow the trading facts, not the other way around. The review should consider trader tax status, account separation, state filing cost, liability goals, estimated taxes, and whether administrative complexity is worth it.

Record structure is equally important. Investment positions should be distinguished from trading positions on the day they are acquired, and multi-broker activity should be reconciled before the return is prepared.

Common Mistakes

• Waiting until after the prior-year return deadline to evaluate the election.

• Failing to file Form 3115 in the change year, creating an unauthorized accounting method change.

• Including investment positions (long-term holdings) in the trading account, contaminating the election.

• Failing to segregate investment versus trading accounts on the books.

• Assuming the election expires annually. Mark-to-market continues until properly revoked; the IRS procedure requires a timely revocation statement and Form 3115, with additional restrictions on certain changes within five years.

The Bottom Line

Section 475(f) is a high-stakes election. For the right active trader — particularly one with significant losses or heavy wash sale exposure — ordinary loss treatment can be valuable. For others, the election can create unfavorable timing or rate results. The decision requires careful modeling of trading patterns, holding periods, account separation, and entity structure.