One sale, two orderings of the same lots, one dollar difference you can trace line by line. That is all this page does.

It will not tell you which method to file, and a lower number in the second column is worth nothing unless your records can name the exact units you sold.

Estimate - not tax advice. Results come only from the figures you enter, cover US federal capital-asset sales within the scope stated below, and are not a filed return or a final position. Your records, your broker's acceptance of a lot instruction and your full transaction history sit outside this page.

Use the cost basis comparison

Enter the asset, sale date and time, units sold, gross USD proceeds, and disposition costs unless the proceeds you entered are already net. Then add the holding wallet or broker account and one row per eligible lot: acquisition date and time, quantity still available, and adjusted USD unit basis including acquisition costs. For a specific-lot scenario, pick the exact lots.

The form rejects a sale larger than your same-asset quantity and flags a blank basis instead of reading it as zero. Estimate only, US federal scope.

What this tool does

Both columns price the same sale. The difference is which eligible lots get consumed and in what order: earliest first on the left, highest adjusted basis first on the right. The output is a gain or loss figure, not tax due, and not a recommendation.

Among the calculators on this site, this one sits upstream of the tax math. It answers a narrow question about lot selection so the number you carry forward is at least internally consistent.

How the lot results are calculated

For each ordering, gain or loss in USD is amount realized minus the adjusted basis of the identified units. For a cash sale, amount realized is cash plus the fair market value of services received to effect the sale, less allocable disposition costs. Costs are subtracted once: if your proceeds figure is already net, leave the cost field empty.

FIFO takes the earliest units in the relevant wallet or account when identification fails. First-acquired, first-disposed is the common default across tax systems when no adequate designation of specific units exists. Highest-basis-first is illustrative specific selection, available only with timely identification and records behind it.

For the identification rules themselves, check the records a lot choice needs.

Worked example

Illustrative arithmetic, not IRS figures. Three lots of one asset sit in a single exchange account. On February 6, 2026 the holder sells 2.00 units for $6,400 gross with $40 in disposition costs, so amount realized is $6,360 in both columns.

The lots: 1.50 units acquired March 4, 2023 at $1,620 per unit; 1.00 unit acquired August 19, 2024 at $2,640; 0.80 units acquired February 11, 2025 at $3,100.

Ordering Lots consumed Units Unit basis Basis subtotal Gain
FIFO Mar 2023 lot 1.50 $1,620 $2,430
FIFO Aug 2024 lot 0.50 $2,640 $1,320
FIFO total 2.00 $3,750 $2,610
Highest basis first Feb 2025 lot 0.80 $3,100 $2,480
Highest basis first Aug 2024 lot 1.00 $2,640 $2,640
Highest basis first Mar 2023 lot 0.20 $1,620 $324
Specific-lot total 2.00 $5,444 $916

Signed difference: $1,694 less gain in the second column. The August 2024 lot only holds 1.00 unit, which is why the second ordering has to reach back into the 2023 lot for the final 0.20. That partial consumption is where hand-built spreadsheets usually break.

Evidence checklist for the second column

  • Asset and the wallet or broker account the units actually sat in.
  • Acquisition source records for each lot: trade confirmation, receipt or transfer record with date and time.
  • Adjusted basis per lot, with acquisition costs already folded in.
  • Time-stamped designation of the specific units, made no later than the disposal.
  • Removal record from your own books, or a broker instruction the broker accepted.
  • Cross-check of the consumed lots against what the broker reported.

Read your result

The left figure is the gain or loss FIFO produces on your entered lots. The right figure is the gain or loss the selected lots produce. The signed difference between them is arithmetic, not tax saved and not a refund.

Treat the right column as a hypothetical until the evidence checklist above is satisfied. Timely identification and records have to support the exact units, or the defensible number is the FIFO one. Once you have a supported result, estimate the tax on the supported sale result.

Rules and source dates

This identification framework applies to 2025 onward (current rule and figures at the IRS digital asset FAQ). The table below is a reference, not a rate table: nothing on this page uses brackets or tax-year thresholds. Pre-2025 unattached basis has its own mechanics, and if that is your situation, check the wallet allocation before trusting any lot list here.

Situation Identification rule Records needed IRS source As of
No valid identification FIFO within the relevant wallet or account Dates, quantities and adjusted basis per lot Digital asset FAQ Sept 26, 2026
2025 disposal from broker custody Identification or a standing order kept on the taxpayer's own records Dated identification or standing-order record Notice 2025-7 Sept 26, 2026
Disposal after December 31, 2025 from broker custody Timely accepted broker instructions with supporting records; the broker's sole offered method controls where only one is offered Instruction confirmation plus your own lot records Digital asset FAQ Sept 26, 2026
Eligible pre-2025 unattached basis Allocated as of January 1, 2025; not computed on this page Unit snapshot per wallet or account and the allocation adopted Rev. Proc. 2024-28, §§5.02(4), 5.02(5)(b) Sept 26, 2026

Edge cases and limits

Blank basis and zero basis are different inputs and the form keeps them apart.

We see the failure every season in test files: a transferred-in position lands with an empty acquisition-cost field, a third-party report reads the blank as a zero-cost position, and the gain comes out far too high.

Leave the field blank and go find the record.

Ask for more units than the lot rows hold and the comparison stops rather than inventing a lot. A same-asset transfer between your own custody locations, with no change in beneficial ownership, is commonly not itself a taxable disposal, so keep it out of the sale input. Lots are eligible only within the wallet or account that held the sold units.

If the broker's report assigns FIFO while you intended a different selection, the difference is a reconciliation problem, not a calculation one. Disposition costs reduce amount realized once and only once.

What this tool cannot tell you

The page cannot look at your contemporaneous records and judge whether a designation was timely. It cannot see the rest of your history, other wallets, or lots you forgot. It cannot guarantee a broker will accept or has accepted an instruction, and it does not determine a filing position.

Where the dollars are consequential, where a position is disputed, or where the underlying records are unreliable, take it to a qualified tax professional with the lot detail in hand.

Common questions

If I never picked lots, which ones does this use? The earliest eligible lots in the relevant wallet or account, which is the FIFO fallback. Units sitting elsewhere do not enter the ordering.

Is highest-cost-first a separate IRS method? No. It is one illustrative way to order specifically identified lots, and it carries the same record requirements as any other specific identification.

Will my exchange use the lots I picked? For a 2025 disposal from broker custody, identification or a standing order kept on your own records is what counts. After December 31, 2025, a timely broker instruction the broker accepts generally governs, and where a broker offers only one method, that method controls.

Why does the calculator show less gain but my form shows something else? Usually missing acquisition basis on the broker's side, or the broker assuming FIFO while you selected different units. Compare the two lot assignments before you change anything: check the broker form against your records.

Start from browse the crypto tax calculators for the rest of the sequence.

From here, the usual next steps are check the broker form against your records when the reported figure disagrees, estimate the tax on the supported sale result once a column holds up, check the records a lot choice needs for the identification rules, and check the wallet allocation for pre-2025 basis.

Pull the records before you pick a column.

Gather the acquisition and identification records, reconcile the broker's lot assignment, then carry a supported gain or loss into the next tax step.

Sources

Estimate - not tax advice. The figures above are produced from the data you entered, cover US federal capital-asset sales in scope, and are neither a filed return nor a final tax position. This page cannot confirm your records, your broker's acceptance of a lot instruction, or your complete transaction history, and no result here promises a tax saving or represents official approval of any ordering.