Capital Gains Tax Lot Optimizer

Compare remaining open lots, not a complete trade ledger

Enter or import the shares still available for sale. Each row is one acquisition lot with a symbol, YYYY-MM-DD date, USD price per share, remaining quantity and total acquisition fees for that remaining lot. Prior sales, splits, transfers and wash-sale basis adjustments must already be reflected in your inputs. Import appends rows and does not reconcile a broker statement or detect duplicates.

CSV requires symbol,date,price,quantity headers and optionally fees. JSON accepts an array of objects or a lots array, using symbol, purchaseDate, purchasePrice, quantity and fees. Files are limited to 2 MB and 5,000 imported rows. Invalid imports leave existing lots unchanged. Empty draft rows must be corrected or deleted before their symbol can be calculated.

What the orderings do

FIFO selects the earliest acquisition dates; LIFO selects the latest. HIFO selects the highest purchase price plus acquisition fees per share. At one sale price, ordering per-share gains from lowest to highest produces exactly the same order as HIFO, so the Loss-First option is not an additional optimization algorithm.

Only lots acquired on or before the sale date are available. A scenario requesting more shares than available stops rather than reporting a partial sale. Partial-lot acquisition fees are allocated in proportion to shares sold. The sale price is assumed net of selling fees per share.

Read the tax figure as a limited scenario

The calculation nets gains and losses within the short- and long-term groups, then offsets opposing group signs. Remaining positive short-term gains use 24%; remaining positive long-term gains use 15%. A net loss produces zero modeled tax, not a refund. These fixed assumptions do not use a tax year, income bracket or filing status.

The lowest modeled result is the lowest among the displayed orderings only. Equal results are ties even if one is highlighted. HIFO can reduce gain without minimizing tax because holding periods differ. Other investments, carryovers, wash sales, NIIT, state taxes and special-property rules can change the result. No manually selected specific-lot workflow or broker submission is implemented.

Broker identification and recordkeeping

For shares held by a broker, the IRS describes identifying the particular shares at the sale or transfer and obtaining written confirmation within a reasonable time. A report downloaded here does not accomplish that identification. See IRS Publication 550 for basis, identification, gain/loss netting and wash-sale rules, and Topic 409 for the general holding-period rule.

Lot calculations and import parsing run in this page. The tool attempts to save lots in this browser's IndexedDB; errors are shown and input remains in the tab. Export Lots saves a copy, while Export in the analysis saves the current scenario. Browser storage may be cleared, and downloaded files are your responsibility. This is not a claim about every site service's data handling.

Frequently Asked Questions