Specific Identification for Crypto: How to Choose Which Lots You Sell

Specific Identification lets you choose exactly which tax lots to sell when disposing of cryptocurrency, potentially minimizing your tax liability by selecting the highest-cost or longest-held lots first. The IRS confirmed in Rev. Rul. 2019-24 and FAQ Q39-Q42 that crypto investors may use Specific Identification as long as they adequately identify the units at the time of sale and maintain proper records.

What Is Specific Identification?

When you buy cryptocurrency multiple times, each purchase creates a separate "tax lot" with its own cost basis and acquisition date. When you later sell, the IRS needs to know which lot you are selling to calculate your gain or loss.

There are two primary accounting methods:

FIFO (First-In, First-Out): The oldest lot is automatically sold first. This is the IRS default method if you do not specify otherwise.

Specific Identification: You choose exactly which lot to sell. This gives you control over both the cost basis and the holding period of each disposal.

For example, suppose you made three purchases of ETH:

• Lot 1: 1 ETH at $1,000 on January 15, 2024
• Lot 2: 1 ETH at $3,500 on March 10, 2024
• Lot 3: 1 ETH at $2,200 on August 5, 2024

If ETH is trading at $2,800 and you sell 1 ETH, your tax outcome depends on which lot you sell:

• FIFO (Lot 1): $2,800 - $1,000 = $1,800 gain (long-term)
• Specific ID (Lot 2): $2,800 - $3,500 = $700 loss (short-term)
• Specific ID (Lot 3): $2,800 - $2,200 = $600 gain (short-term)

The difference between the best and worst outcome is $2,500 in reportable gain. At a 24% federal tax rate, that is a $600 difference in tax owed from a single 1 ETH sale.

IRS Requirements for Specific Identification

The IRS has established clear requirements for using Specific Identification with cryptocurrency, drawn from existing securities rules adapted for digital assets.

Adequate Identification at Time of Sale

According to IRS FAQ Q39 (updated 2024), you must identify the specific units being sold at the time of the transaction. This means before or at the moment of disposal, not retroactively.

For crypto held on an exchange, adequate identification requires specifying:

• The date and time of the original purchase
• The cost basis of the units being sold
• The quantity being disposed of

For crypto held in a personal wallet, you must be able to identify the specific units by the transaction hash, wallet address, or other unique identifier.

Record-Keeping Requirements

The IRS requires you to maintain records that show (per IRS FAQ Q42):

1. The date and time each unit was acquired
2. Your cost basis and the fair market value at acquisition
3. The date and time each unit was sold, exchanged, or disposed of
4. The fair market value at disposal and the amount received
5. The specific lot identified for each disposal

These records must be retained for at least three years after filing (the standard statute of limitations under IRC Section 6501), though the IRS recommends keeping crypto records for six years if you underreported income by more than 25%.

Consistency Requirement

While the IRS does not prohibit switching between FIFO and Specific ID across tax years, frequent switching can raise audit flags. The safer approach is to pick a method and use it consistently. If you do switch, document the reason and the date you changed methods.

It is important to note that you cannot retroactively change the method for past tax years. If you filed using FIFO for 2024, you cannot amend to Specific ID for 2024 transactions.

LIFO and HIFO as Specific ID Variants

Two common strategies built on Specific Identification deserve special attention:

HIFO (Highest-In, First-Out)

HIFO sells the lot with the highest cost basis first, minimizing your gain (or maximizing your loss) on each sale. This is generally the most tax-efficient strategy when you are selling at a profit, because it reduces the taxable gain.

However, the IRS does not recognize HIFO as a standalone method. It is a variant of Specific Identification where you consistently choose the highest-cost lot. You must still meet all Specific ID documentation requirements.

LIFO (Last-In, First-Out)

LIFO sells the most recently purchased lot first. This can be advantageous when recent purchases have a higher cost basis than older ones (common in a rising market). LIFO is also a variant of Specific Identification under IRS rules.

A critical distinction: the IRS only officially recognizes FIFO and Specific Identification for crypto (per Notice 2014-21 and subsequent guidance). LIFO and HIFO are permissible as long as they are implemented as Specific ID with proper lot identification. dTax labels these as "Specific ID (LIFO)" and "Specific ID (HIFO)" on generated reports to maintain IRS compliance.

Practical Examples: FIFO vs. Specific ID

Example 1: Maximizing a Loss

You purchased BTC across three months in early 2025:

• January: 0.5 BTC at $95,000 ($47,500 cost)
• February: 0.5 BTC at $98,000 ($49,000 cost)
• March: 0.5 BTC at $72,000 ($36,000 cost)

In December 2025, BTC is at $80,000 and you sell 0.5 BTC.

FIFO result: Sell January lot. Proceeds $40,000 - Cost $47,500 = $7,500 loss. Specific ID (HIFO): Sell February lot. Proceeds $40,000 - Cost $49,000 = $9,000 loss.

Specific ID produces an additional $1,500 loss, saving $360 at a 24% tax rate.

Example 2: Achieving Long-Term Capital Gains

You hold two lots of SOL:

• Lot A: 100 SOL bought November 2024 at $20 ($2,000 cost) - held over 1 year
• Lot B: 100 SOL bought September 2025 at $180 ($18,000 cost) - held under 1 year

You sell 100 SOL in December 2025 at $200 ($20,000 proceeds).

FIFO result: Sell Lot A. $20,000 - $2,000 = $18,000 long-term gain. Tax at 15% = $2,700. Specific ID (Lot B): $20,000 - $18,000 = $2,000 short-term gain. Tax at 24% = $480.

Despite paying a higher tax rate on short-term gains, Specific ID saves $2,220 because the gain is dramatically smaller. This demonstrates that cost basis often matters more than holding period.

Example 3: Triggering Long-Term Treatment

Sometimes the opposite strategy is better. If you have a modest gain, choosing a lot held over one year can be advantageous:

• Lot X: 1 ETH at $2,000, held 14 months (long-term)
• Lot Y: 1 ETH at $2,100, held 3 months (short-term)

Selling 1 ETH at $2,500:

FIFO (Lot X): $500 gain at 15% long-term rate = $75. Specific ID (Lot Y): $400 gain at 24% short-term rate = $96.

Here, FIFO (which happens to select the long-term lot) actually produces a lower tax bill. The lesson: always compare both the gain amount and the applicable rate.

When Specific ID Saves the Most Money

Specific Identification is most valuable in these scenarios:

High-frequency traders who accumulate many lots at different prices throughout the year. With dozens or hundreds of lots, the spread between the highest and lowest cost basis can be substantial.

Long-term holders who DCA (Dollar Cost Average) and periodically sell. DCA creates many lots at varying prices, and Specific ID lets you cherry-pick the most tax-efficient lots.

Year-end tax planning where you need to realize specific gains or losses to offset other income. Specific ID gives you precision control over your tax position.

Mixed holding periods where some lots qualify for long-term capital gains rates (15% for most taxpayers per IRC Section 1(h)) while others are short-term (taxed as ordinary income up to 37%).

According to a study by CoinTracker analyzing 500,000 tax returns, users who switched from FIFO to HIFO (a Specific ID variant) reduced their reported capital gains by an average of 28%.

dTax's Lot Selection and Wallet-Siloed Cost Basis

dTax's open-source tax engine implements Specific Identification with full lot-level tracking:

Lot-Level Visibility: Every purchase creates a distinct tax lot with its own cost basis, acquisition date, and source wallet. When you sell, dTax shows all available lots and their tax impact before you commit.

Wallet-Siloed Cost Basis: dTax tracks cost basis separately for each wallet and exchange. This is critical because the IRS requires that cost basis be tracked at the account level for covered securities under 1099-DA reporting. When you transfer between wallets, dTax maintains the original lot information through the transfer.

Method Comparison: Before generating your tax report, dTax can calculate your total liability under FIFO, LIFO, and HIFO, letting you compare outcomes and choose the method that minimizes your taxes.

Audit Trail: Every lot selection is logged with a timestamp, creating the documentation trail the IRS requires for Specific Identification. If audited, you can produce a complete record showing which lots were identified for each sale and when.

Form 8949 Output: dTax generates Form 8949 with each transaction on a separate line, sorted by box category (A through F), with cost basis, proceeds, and any adjustment codes. The output is available as CSV, PDF, or TXF format for TurboTax import.

FAQ

Do I need to notify the IRS that I am using Specific Identification?

No, you do not need to file any special election or notification with the IRS to use Specific Identification for crypto. You simply apply the method when reporting on Form 8949 and maintain adequate records. Unlike some investment accounts that require a broker election for Specific ID, crypto held in personal wallets has no broker notification requirement. Just ensure your records clearly show which lots were identified at the time of each sale.

Can I use Specific Identification retroactively for past tax years?

No. The IRS requires that you identify the specific lots at the time of the transaction, not after the fact. If you filed a prior year using FIFO, you cannot amend your return to retroactively apply Specific ID to those transactions. You can, however, begin using Specific ID for future transactions at any time. Going forward, ensure your tax software or records identify the specific lots before or at the time of each sale.

What records do I need to keep for Specific Identification?

You must maintain records showing: (1) the date and time each unit was acquired, (2) the cost basis at acquisition, (3) the date and time of disposal, (4) the fair market value and amount received at disposal, and (5) which specific lots you identified for each sale. Keep these records for at least three years after filing (six years if underreporting exceeds 25%). Digital records such as exchange transaction logs, blockchain transaction hashes, and tax software reports all qualify as adequate documentation.