By the ChainTax Editorial Team · Updated June 2026 · Researched from authoritative sources. General information, not professional advice.
When you sell, trade, or spend cryptocurrency, the size of your taxable gain does not depend only on the sale price. It also depends on which units you are treated as having sold — and that is decided by your cost basis method. If you have bought the same coin at several different prices over time, the method you use can dramatically change the number you report to the Internal Revenue Service (IRS). This guide explains the main methods, the records the IRS expects, and the recent shift to per-wallet basis tracking. It is written for a general U.S. audience.
Cost basis is what you paid to acquire an asset, including transaction and acquisition fees. If you buy 1 ETH for $1,800 and pay a $20 exchange fee, your cost basis in that unit is $1,820. When you later dispose of the asset, your gain or loss is the proceeds minus your cost basis. Higher basis means a smaller gain (or a larger loss); lower basis means a larger gain. The IRS treats crypto as property, so these are the same general basis rules that apply to stock and other capital assets, reported on Form 8949 and Schedule D.
The wrinkle is that most people do not buy crypto in a single lump. They accumulate the same coin across many purchases at many prices. When you sell only part of your holdings, the law has to decide which of those lots you sold. That decision is the cost basis method, and it is where real dollars are won or lost.
Under FIFO, the first units you bought are treated as the first units you sell. It is the most common default and the one the IRS generally assumes if you have not made and documented a different, valid choice. FIFO is simple and easy to defend, but in a rising market it tends to match your oldest, cheapest coins against your sale — which often produces the largest taxable gain. On the upside, those oldest lots are more likely to have been held more than a year, which can qualify the gain for lower long-term rates.
LIFO does the reverse: the most recently acquired units are treated as sold first. In a market that has been climbing, your newest lots usually have the highest basis, so LIFO can shrink your gain compared with FIFO. The trade-off is holding period — recently bought lots are more likely to be short-term, taxed at ordinary income rates. LIFO can be valid as a form of specific identification, but only if you keep the records described below.
HIFO deliberately sells your highest-basis units first, regardless of when you bought them. Because it matches the most expensive lots against your sale, HIFO generally produces the smallest taxable gain in the year of sale, which is why many traders prefer it. HIFO is not a separate blessing in the tax code — it is a way of applying specific identification, so it carries the same recordkeeping burden. It can also pull short-term lots forward and use up your long-term inventory, so the lowest current-year gain is not always the best long-term outcome.
Specific Identification (Spec ID) lets you choose exactly which units you are selling, lot by lot. FIFO, LIFO, and HIFO are all really just rules for how you apply Spec ID. The IRS allows it, but only if you can adequately identify the units. In practice that means contemporaneous records showing, for each specific unit:
If you cannot identify the specific units you sold, the IRS treats you as having used FIFO by default. The agency's digital-asset guidance and its FAQ on digital assets describe these identification requirements; confirm the current version before you rely on a non-FIFO method.
Suppose you bought 1 BTC three times, then sold 1 BTC for $60,000 in proceeds. Your three lots were:
| Method | Lot sold | Cost basis | Proceeds | Gain | Likely treatment |
|---|---|---|---|---|---|
| FIFO (default) | Lot A | $20,000 | $60,000 | $40,000 | Long-term |
| LIFO | Lot C | $52,000 | $60,000 | $8,000 | Short-term |
| HIFO | Lot C | $52,000 | $60,000 | $8,000 | Short-term |
| Specific ID | Lot B (chosen) | $35,000 | $60,000 | $25,000 | Long-term |
The exact same $60,000 sale produces a $40,000 gain under FIFO but only an $8,000 gain under HIFO — a difference of $32,000 in reported gain. Specific ID here lets you split the difference and pick Lot B, accepting a moderate $25,000 gain in exchange for keeping long-term treatment, which is often taxed at a lower rate than the short-term $8,000 result. These figures are illustrative only; your real numbers and rates will differ.
The general principle is that selling higher-basis lots reduces your current-year gain. But basis is not the only lever — holding period matters too. A lot with a slightly lower basis that qualifies for long-term rates can sometimes beat a higher-basis short-term lot once the tax rate is applied. Good planning weighs both the gain size and the likely rate, which is exactly the kind of side-by-side comparison that Spec ID makes possible.
Historically many taxpayers tracked basis on a "universal" basis — pooling all units of a coin across every wallet and exchange. The IRS has been moving away from that cross-wallet approach toward per-wallet (per-account) basis tracking, where you account for the units held in each wallet or account separately rather than as one global pool. This affects which lots are even available to identify when you sell from a particular account. The IRS provided transition guidance and safe-harbor relief for allocating existing basis as the rules changed, but the details and timing matter. Do not assume the old universal method still applies — verify the current per-wallet rules and any remaining transition or safe-harbor relief with the IRS or a CPA before you file.
Whatever method you use, you generally must apply it consistently and be able to support it with records. You cannot retroactively re-pick the most favorable method for a sale after the fact without the documentation to back the identification at the time. Switching methods or accounting approaches can have its own rules, so keep your method, your lot selections, and your supporting data aligned across the year.
Broker reporting is changing the landscape. The IRS introduced Form 1099-DA, a dedicated information return for digital asset transactions, so brokers and certain platforms report customer activity to you and to the IRS. Over time this includes gross proceeds and, increasingly, cost basis. A key gap: basis acquired before the broker reporting rules took effect (pre-2025 lots) may be missing or incomplete, especially for coins transferred in from other wallets. If your 1099-DA shows proceeds but no basis, the burden is on you to supply accurate basis — otherwise the IRS may effectively treat your basis as zero, inflating your gain.
Applying any method correctly across hundreds of transactions, multiple wallets, and per-wallet tracking by hand is error-prone. Dedicated crypto-tax software ingests your transaction history, maintains lot-level records with acquisition dates and basis, applies your chosen method consistently, and produces Form 8949 detail. That lot-level audit trail is also what makes a Specific Identification or HIFO position defensible if the IRS asks. Software does not replace professional advice, but it makes accurate, method-consistent reporting realistic.
Special basis rules apply when you do not buy crypto yourself. For gifted crypto, you generally take a carryover of the giver's cost basis (with special dual-basis rules if the asset had lost value at the time of the gift). For inherited crypto, the basis is generally "stepped up" to the fair market value on the date of the decedent's death, and inherited property is typically treated as long-term. These rules are nuanced — confirm the specifics with the IRS or a tax professional.
A reminder on authority: the points above trace back to IRS guidance, including the IRS cost-basis and specific-identification rules, the IRS FAQ on digital assets, Form 8949, the new Form 1099-DA, and the IRS per-wallet basis rules and related transition relief. Tax law changes, and the IRS continues to update its digital-asset guidance. Always confirm current rules with the IRS directly or a qualified CPA before filing.
In a rising market, HIFO usually produces the smallest current-year gain because it sells your highest-basis lots first. But "lowest tax" also depends on holding period and rates — a long-term lot can beat a lower-basis short-term lot once the rate applies. Compare both, and remember any non-FIFO method requires Specific Identification records.
Generally yes, if you can adequately identify the specific units sold with records of the acquisition date and time, basis, sale date and time, and proceeds for each unit. Without that identification, the IRS treats you as using FIFO by default. Verify the current requirements with the IRS.
It means accounting for basis separately within each wallet or account rather than pooling all units across every wallet. The IRS has moved away from the older universal approach toward per-wallet tracking and issued transition and safe-harbor relief during the change. Confirm the current rules and any relief that applies to your existing lots with the IRS or a CPA.
Form 1099-DA may show proceeds without basis, particularly for pre-2025 lots or coins transferred in from elsewhere. You are responsible for supplying accurate basis on Form 8949; if you cannot, basis may be treated as zero, which inflates your gain. Keep your own records or use crypto-tax software to reconstruct them.
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