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Crypto Cost Basis Explained: What It Is and Why It Matters

Cost basis is what you paid for crypto, and it decides your taxable gain when you dispose of it. Here is how cost basis and accounting methods work, with US and SA notes, and how Coinfig handles it.

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Crypto Cost Basis Explained: What It Is and Why It Matters

This is general educational information, not tax advice. Crypto tax rules differ by country and change. Confirm the rules for your jurisdiction and tax year, or speak with a qualified tax practitioner. (Reviewed 2026-06-24.)

Direct answer

Cost basis is what you paid to acquire a crypto asset, including fees. When you dispose of that asset, your taxable gain or loss is the proceeds minus the cost basis. If you receive crypto as income, your basis is its value when you received it. Getting cost basis right is what makes your reported gains accurate, and missing basis is one of the most common causes of overpaying or misreporting crypto tax.

Why this matters

Your gain is only as accurate as your cost basis. If you cannot show what you paid, a tax authority may treat your basis as low or zero, which inflates your taxable gain. People most often run into trouble when they have bought the same asset many times at different prices, moved it between platforms, or lost records when an exchange shut down. In each case, the question is the same: which units did you sell, and what did they cost?

How it works

Basis on acquisition

When you buy crypto, your basis is the purchase price plus acquisition fees. When you receive crypto as income (for example mining, staking, or payment), your basis is its fair market value at the time you received it.

Choosing which units you sold

If you hold many lots of the same asset bought at different prices, an accounting method decides which lot you are deemed to sell:

  • FIFO (first in, first out): the oldest units are sold first.
  • LIFO (last in, first out): the newest units are sold first.
  • HIFO (highest in, first out): the highest-cost units are sold first.
  • Specific identification: you identify the exact units sold.

Which methods are permitted, and which is the default, depends on your jurisdiction. In the United States, for example, FIFO is the default, specific identification must be made before or at the time of sale, and from 1 January 2025 cost basis must be tracked per wallet or account rather than across your whole portfolio. In South Africa, base cost and the relevant approach follow SARS rules. The method you choose can change your tax, so confirm what applies to you.

Practical example or analogy

Cost basis is the receipt for what you paid. Imagine buying the same item on three occasions at different prices, then selling one. To work out your profit, you need to know which one you sold and what it cost. Without the receipt, you cannot prove your cost, and you may be taxed as if it were free. Crypto works the same way, just at a larger scale across many transactions.

Key steps or considerations

  1. Record every acquisition with the date, amount, price, and fees.
  2. Capture income at receipt value, since that becomes the basis for income crypto.
  3. Pick a method you are allowed to use in your jurisdiction, and apply it consistently.
  4. Track per source where required, such as the US per-wallet rule from 2025.
  5. Recover missing basis early. If an exchange closed, reconstruct records from your own history before you file.

How Coinfig supports cost basis

Cost basis is hard mainly because the data is scattered and the method has to be applied consistently. Coinfig is built for both.

  • It assembles the history. Coinfig imports from exchanges and wallets using read-only, encrypted keys, plus CSV, so the acquisitions and fees that make up your basis are gathered in one place.
  • It applies a method, transparently. Coinfig supports configurable, jurisdiction-aware accounting methods (FIFO, LIFO, HIFO) and shows the full working behind every figure, so the basis is not a black box.
  • It flags missing data. Through its Data Completeness Score, Coinfig surfaces gaps and unmatched transfers before you rely on the numbers, which is exactly where missing basis hides.

Coinfig is built for South African filers. For tax teams that need multi-jurisdiction treatment and ERP exports, Sixpence offers LedgerTax, which applies jurisdiction-specific treatments and configurable methods. Coinfig is a calculation and reporting tool, not tax advice; the final review stays with you or your practitioner.

Limitations and compliance considerations

  • Methods and defaults vary by jurisdiction. FIFO, specific identification, and per-wallet rules are US specifics; other countries differ. Use what applies to you.
  • Records are everything. A method cannot fix missing acquisition data; the fix is complete records.
  • Rules change. The US per-wallet requirement from 2025 is a recent example. Check the current rules for your country and year.
  • This is general information, not tax advice.

Frequently asked questions

What is cost basis in simple terms? It is what you paid for an asset, including fees, used to work out your gain when you sell.

What if I received the crypto for free or as income? Your basis is its value at the time you received it, and that receipt is also usually taxable as income.

Which accounting method should I use? It depends on your jurisdiction and what you are permitted to use. FIFO is the US default; specific identification has strict timing rules there. Confirm for your country.

What if I do not know my cost basis? Reconstruct it from your transaction history across exchanges and wallets. If basis cannot be shown, you may be taxed on a larger gain.

Conclusion

Cost basis is the foundation of an accurate crypto tax return: what you paid, which units you sold, and the method you applied. The practical battle is gathering complete records and applying a method consistently. Coinfig supports both, by importing your history, applying a transparent accounting method, and flagging the gaps where missing basis hides. To see your own figures with the working shown, start with the free Coinfig workspace at coinfig.tax.

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