When you sell, swap, or spend cryptocurrency, the IRS expects you to report a gain or loss — and the size of that gain or loss depends entirely on which coins you’re considered to have sold. That decision is controlled by your cost basis accounting method. Choosing between FIFO, HIFO, and Specific Identification isn’t a minor bookkeeping detail; it can shift your tax bill by hundreds or thousands of dollars on the same set of transactions. This article explains how each crypto cost basis method works, when each one benefits you, and what the IRS currently allows US taxpayers to do heading into the 2026 tax year.
Why Cost Basis Method Matters for Crypto Taxes
Cost basis is the original value of an asset for tax purposes — typically what you paid for it, including fees. When you dispose of crypto, your taxable gain equals the proceeds minus the cost basis of the specific units disposed. The method you use to identify which units were sold determines which cost basis figure enters that calculation.
The IRS treats cryptocurrency as property under IRS Notice 2014-21 and confirmed in subsequent guidance including Revenue Ruling 2023-14. Because crypto is property, the same cost basis rules that apply to stocks and mutual funds apply here — but with important nuances around how you track and document your choice.
The Three Primary Cost Basis Methods
FIFO — First In, First Out
Under FIFO, the oldest coins you acquired are treated as the first ones sold. If you bought 1 BTC in January 2021 and another in March 2024, selling 1 BTC today means the IRS treats you as having sold the January 2021 lot.
- Default method: If you don’t specify a method, the IRS and most tax software will default to FIFO.
- Long-term gains likely: Older lots are often held longer than one year, qualifying for lower long-term capital gains rates (0%, 15%, or 20% depending on income).
- Higher gains possible: If older lots had a much lower purchase price, FIFO can produce the largest taxable gain during a bull market.
HIFO — Highest In, First Out
HIFO sells the coins with the highest cost basis first, minimizing your recognized gain (or maximizing your recognized loss) on each transaction. If you hold lots purchased at $60,000, $30,000, and $15,000 per BTC, HIFO would assign the $60,000 lot to the next sale.
- Minimizes taxable income: Particularly effective during market appreciation when you have a mix of high- and low-basis lots.
- Requires specific ID compliance: HIFO is not a standalone method the IRS names explicitly. To use it legally, you must meet the Specific Identification requirements (discussed below).
- Gain deferral, not elimination: Lower-basis lots remain in your portfolio and will eventually be taxed.
Specific Identification (Spec ID)
Specific Identification lets you choose exactly which lot is sold at the time of each transaction. This is the most flexible method and the legal mechanism that makes HIFO (and LOFO, or any custom ordering) possible.
The IRS permits Specific Identification for cryptocurrency if you can demonstrate, at or before the time of sale, which specific units you are disposing of. According to IRS Publication 550 (which covers investment income and expenses and is applied by analogy to crypto property), adequate identification requires records of the date acquired, amount paid, and identifying information for each lot.
IRS Requirements for Specific Identification
The IRS has not issued crypto-specific Specific ID guidance beyond treating crypto as property, so practitioners apply the stock identification rules by analogy. To satisfy Spec ID you generally need:
- Records of each acquisition: date, amount, price paid, and transaction hash or exchange confirmation.
- A contemporaneous record at the time of sale indicating which lot(s) you are disposing of — not reconstructed after the fact.
- Confirmation from your exchange or wallet that the specified lot was actually transferred (difficult on-chain without UTXO-based tracking or exchange-level lot selection tools).
Practically, most major centralized exchanges (Coinbase, Kraken) allow you to select your cost basis method in account settings. Coinbase’s tax documentation explicitly states that users can switch between FIFO, HIFO, and LIFO at the account level, which it treats as satisfying contemporaneous identification for transactions on that platform.
FIFO vs HIFO: Which Saves More Tax?
Bull Market Scenario
Suppose you bought 2 ETH: one at $1,000 (January 2023) and one at $3,000 (November 2024). You sell 1 ETH today at $4,000.
- FIFO result: Gain = $4,000 − $1,000 = $3,000 (long-term, held >1 year)
- HIFO result: Gain = $4,000 − $3,000 = $1,000 (short-term, held <1 year)
In this case HIFO produces a smaller nominal gain, but that gain is short-term (taxed as ordinary income). FIFO produces a larger gain, but at the preferential long-term rate. Depending on your marginal rate, FIFO could actually generate a lower tax bill. This is the critical nuance most simplified guides miss.
Bear Market / Loss Harvesting Scenario
If prices are below your average purchase price, HIFO accelerates the recognition of your largest losses, which can offset gains elsewhere. Tax-loss harvesting with Specific ID is a common strategy, though the wash-sale rule does not currently apply to cryptocurrency under the Internal Revenue Code (as of 2025, though legislative proposals have sought to change this — monitor IRS announcements for 2026 updates).
Tracking Across Multiple Wallets and Exchanges
The complexity of cost basis accounting multiplies when you move assets between wallets. The IRS requires that you track basis at the asset level regardless of where it is held. Moving crypto from Coinbase to a MetaMask wallet does not reset your cost basis — the original acquisition date and price follow the asset.
This creates a documentation challenge: on-chain transactions don’t record dollar cost. You must maintain off-chain records. Tools like Koinly, CoinTracker, and TaxBit attempt to reconcile exchange records with on-chain data, but they are only as accurate as the data you feed them. The IRS Form 1099-DA, required of brokers beginning in tax year 2025, will report proceeds and, in some cases, cost basis for custodied assets — but self-custodied wallets remain your personal record-keeping responsibility.
What This Means for You
Before filing your 2025 return (due in 2026) or making disposal decisions this year, take these concrete steps:
- Set your method explicitly in each exchange’s settings before year-end. Don’t leave it as an unexamined default.
- Model both FIFO and HIFO using your actual lot history — factor in whether gains are short-term or long-term before assuming HIFO always wins.
- Maintain contemporaneous records of any Specific ID elections, especially for DeFi or self-custody transactions where no platform records the choice for you.
- Watch for wash-sale legislation. Congressional proposals have repeatedly targeted crypto wash sales. If enacted, loss harvesting strategies will face the same 30-day repurchase restriction as securities.
- Consult a CPA or tax attorney with crypto experience before switching methods mid-year on a large portfolio. Method changes can have retroactive implications depending on how your records are structured.
Cost basis accounting is not glamorous, but it is the single most controllable variable in your crypto tax liability. The method you choose — or fail to choose — is a decision with real dollar consequences every time you execute a trade.
