1. Your accounts
One row per account or contract group: label, realized (box 8), prior year-end unrealized (box 9), current year-end unrealized (box 10). CSV or pasted spreadsheet range; a header row is optional. Losses as -500 or (500).
Choose a file or paste the rows, then click Calculate.
Result
| Account | Realized | Prior unrealized | Current unrealized | Aggregate (box 11) |
|---|
How it works, and what it leaves out
- Aggregate: realized (8) minus prior year-end unrealized (9) plus current year-end unrealized (10), per row, then summed.
- Split: 60% long-term, 40% short-term, regardless of holding period.
- Tax: net × (0.6 × long-term rate + 0.4 × ordinary rate); compared with net × ordinary rate. The 3.8% net investment income tax, if ticked, is added to both rates.
- Rules reviewed: 2026-10-08, by the author from IRC section 1256, Form 6781 and its instructions, and Form 1099-B instructions, not by a tax professional. Rules can change.
- Not decided: which of your contracts qualify, straddle and mixed-straddle rules, the section 988 currency election, the trader tax status election (section 475), capital loss limits against other gains, state tax, and the exact bracket your gain pushes you into.
Common questions
What is a Section 1256 contract?
Regulated futures contracts, broad-based index options such as SPX, NDX and VIX, dealer equity options and some foreign currency contracts. They are marked to market on the last business day of the year, as if sold at fair value, and the result is reported on Form 6781.
What is the 60/40 rule?
Net gains and losses on Section 1256 contracts are treated as 60% long-term and 40% short-term capital gain or loss, however long you held the position. For a high earner that blended rate is lower than the ordinary short-term rate that applies to day trading stocks or options on single stocks.
Where do the numbers come from?
From Form 1099-B. Box 8 is realized profit or loss, box 9 is last year's year-end unrealized, box 10 is this year's year-end unrealized, and box 11 is the aggregate: box 8 minus box 9 plus box 10. Enter boxes 8, 9 and 10 per account and the page computes the aggregate for you so you can compare it with box 11.
Can I carry a 1256 loss back?
Yes, by election on Form 6781 Part II: a net 1256 loss can be carried back three years against net 1256 gains instead of only being carried forward. Whether that pays depends on your earlier years; ask a tax professional.
Does this include SPY, QQQ or single-stock options?
No. ETF shares and options on ETFs or single stocks are ordinary capital assets and are not 1256 contracts. Only the contracts listed above qualify, and your broker's 1099-B tells you which.
Is my data uploaded anywhere?
No. It is read in your browser and nothing is sent; a test in the code asserts there are no network calls.