Crypto cost basis, explained: how to calculate it without losing your mind

The IRS has treated cryptocurrency as property (not currency) since IRS Notice 2014-21. That legal classification has a big downstream consequence: every time you sell, swap, or spend crypto, you've triggered a potentially taxable event. The tax due is based on the difference between your cost basis (what you paid) and your proceeds (what you received, in USD terms at the time of the transaction).

Most crypto tax pain comes from one problem: people don't have a clean record of cost basis across multiple exchanges, wallets, and years. This guide walks through what cost basis actually is, the three IRS-accepted methods for calculating it, and what happens when your records are imperfect (spoiler: you have options).

What cost basis really means

Cost basis is your adjusted purchase price in USD. For a crypto buyer, it's:

(USD spent) + (fees paid)

For crypto received in other ways, the rules vary:

| How you acquired crypto | Cost basis | |---|---| | Bought with USD | USD paid + fees | | Bought with other crypto (swap) | Fair market value of crypto given up at time of swap | | Received as payment for goods/services | FMV of crypto received at time of receipt | | Mined or staked | FMV at time you received it (and this is also ordinary income) | | Received as a gift | Donor's basis (if higher than FMV at gift, use FMV for loss purposes only) | | Received via hard fork | FMV at time the new coin came into your control | | Received via airdrop | FMV at time you had dominion and control |

When you dispose of that crypto, you realize a gain or loss equal to:

Proceeds (USD value at disposal) − Cost Basis = Capital Gain/Loss

If held more than 12 months: long-term capital gain (0%, 15%, or 20% federal rate depending on income)

If held 12 months or less: short-term capital gain (taxed as ordinary income, up to 37%)

The three IRS-accepted accounting methods

When you own multiple units of the same crypto (e.g., you bought BTC at $30k, $45k, and $60k) and sell some, you have to pick which specific units you're selling. The IRS allows three methods:

1. FIFO (First In, First Out)

The default. The units you bought first are deemed sold first.

Pros: Simplest. Easy to track. IRS-approved by default.
Cons: In a rising market, you realize the largest gains first = more tax now.
When to use: Default choice if you don't actively manage cost basis.

2. Specific Identification (SpecID)

You pick which specific units you're selling — usually picking the highest-cost units first to minimize gain.

Pros: Minimizes taxable gains. Maximizes tax-loss harvesting opportunities.
Cons: You must be able to prove which specific units you sold. This means detailed records at the transaction level, including wallet addresses and lot IDs.
When to use: Recommended for anyone with meaningful trading activity. Requires software.

3. HIFO (Highest In, First Out)

A subset of SpecID that systematically picks the highest-cost units first.

Pros: Often minimizes tax. Algorithmically consistent.
Cons: Still requires detailed records. Not officially a separate IRS method but is a form of SpecID.
When to use: Common in tax software defaults. Works well for most active traders.

What about LIFO or average cost?

LIFO (Last In, First Out) is allowed for general property but not for crypto per IRS guidance.
Average cost is allowed for mutual funds but not for crypto.

Don't use these methods for crypto, no matter what you saw on Twitter.

The records you need

The IRS wants to see, for every transaction:

Date and time of the transaction
Type of transaction (buy, sell, swap, transfer, etc.)
Asset and amount (e.g., 0.5 BTC)
USD value at the time (proceeds or cost)
Fees paid
Wallet/exchange where it occurred
Lot identification (for SpecID/HIFO)

Most exchanges provide CSVs with most of this data. The messy cases are:

Transfers between your own wallets (not taxable events but must be tracked so you don't double-count the next disposal)
DeFi transactions (swaps, liquidity pools, yield farming — often no clean CSV)
NFT transactions (same rules as crypto but each NFT is a unique lot)
Gas fees (these adjust basis or are cost of disposal depending on context)

What if your records are incomplete?

Very common. The IRS expectation is that you make a good-faith reasonable estimate using whatever records you can reconstruct. In practice:

Pull every exchange CSV you can. Most exchanges keep 2-7 years of history on request.
Query the blockchain directly for on-chain transactions. Tools like Etherscan, Solscan, and commercial crypto tax software do this.
Reconstruct pricing using historical price data from CoinGecko, CoinMarketCap, or your tax software.
Where truly unrecoverable, document your estimation methodology. If audited, showing a clear reconstruction process is much better than random guessing.

The IRS has signaled in recent guidance that zero cost basis is the fallback when truly no records exist — meaning you're taxed on 100% of proceeds as gain. Avoid this by reconstructing whenever possible.

The wash sale rule: does it apply to crypto?

Not yet, as of April 2026. The wash sale rule (which disallows loss recognition if you repurchase within 30 days) currently applies only to "securities" — and crypto is "property," not a security.

This means crypto tax-loss harvesting is more flexible than stock harvesting: you can sell at a loss and immediately rebuy without losing the loss.

Proposed legislation has repeatedly tried to close this loophole. Expect the rule to eventually apply to crypto — check current year when filing.

The new 1099-DA reporting (2025+)

Starting with 2025 transactions, crypto brokers must issue Form 1099-DA reporting your proceeds and (eventually) cost basis to both you and the IRS. Some key points:

2025 filing: Proceeds only (no cost basis)
2026+ filing: Proceeds and cost basis (where broker has it)
Only covers broker transactions — self-custody and DeFi are not covered
Must match your return — if you report numbers different from the 1099-DA, expect an IRS notice

If you trade across multiple exchanges and self-custody wallets, you'll receive multiple 1099-DAs that each see only part of your picture. You're responsible for reconciling them into one consistent cost-basis ledger across all venues.

What this looks like in practice

Two quick examples.

Example A: Simple HODLer

Bought 1 ETH for $2,000 in March 2022
Held in MetaMask
Sold 1 ETH for $3,500 in April 2026

Cost basis: $2,000. Proceeds: $3,500. Long-term capital gain: $1,500. If filer is in the 15% LTCG bracket, tax owed: $225.

Example B: Active trader across exchanges

Dozens of purchases across Coinbase, Kraken, Binance.US over 3 years
Several DeFi swaps on Uniswap
Received ~100 airdrops (some valuable, most worthless)
Self-custody movements between wallets

This person needs crypto tax software. Manual reconstruction is possible but takes 20-40 hours and is error-prone. Commercial options include CoinTracker, Koinly, CoinLedger, and a few others — all ingest exchange CSVs and on-chain data, apply the cost-basis method you choose, and generate IRS Form 8949.

Folio Tax does this natively — continuous cost-basis tracking, 1099-DA reconciliation, and export to your CPA in IRS-ready format.

Takeaways

Crypto is property; every disposal is a taxable event
Cost basis = USD paid + fees; for non-purchases, FMV at receipt
Three accounting methods: FIFO (default), SpecID, HIFO — no LIFO or average cost
Keep per-transaction records; reconstruct from exchange CSVs and on-chain data if missing
1099-DA reporting is phasing in 2025-2026
Crypto wash sale rule may tighten — check current year

None of this is tax advice; consult a CPA for your specific situation. Folio Tax handles the ledger work so your CPA has clean numbers to file with.