Missing Crypto Cost Basis: 6 Steps When an Exchange History Is Gone

Missing Crypto Cost Basis: 6 Steps When an Exchange History Is Gone

The exchange shut down, or you lost the login, or the account closed years ago. Now you want to sell, and you cannot say what you paid. Missing crypto cost basis is a records problem, and it is usually fixable in part before it becomes a tax problem.

Here are six steps, in the order to do them. It is a numbered list of steps, not a ranking. Each one has a limit, because no step recovers everything.

If you want a firm that works on crypto tax, Crypto Tax Made Easy is based in Little Silver, New Jersey, and fits the investor who holds assets across several wallets and exchanges and may need a CPA-level conversation about the gaps. Its profile does not say it offers record reconstruction, so treat that as a question to ask. Crypto Tax Made Easy is a paid featured member of Sam's List. The full methodology is at the end.

Why Missing Crypto Cost Basis Matters Before You Sell

Basis is generally what you paid for an asset, including fees. Your gain is the sale price minus basis. If you cannot show basis, the number on your return is a claim you may not be able to support.

A taxpayer generally bears the burden of substantiating basis, and records generally should support the figures on a return. That is the standard you are working toward. What counts as enough support for your facts is a question for a CPA.

The limitation: some of it may not be rebuildable, so start early.

1. Pull Every Exchange Transaction History Export and Statement You Can

Start with what exists. An exchange transaction history export is often a CSV of trades, deposits and withdrawals. Search old email for the exchange's name and for "statement".

Then go to the outside record. Bank and card statements show the dates and dollar amounts you moved to buy crypto. These do not show which coin you bought, but they anchor when money left and how much.

If the exchange is closed, ask support or any successor whether account data can still be requested.

The limitation: a bank line proves a deposit, not a purchase price per coin. Treat these as supporting evidence that you will match to on-chain data in the next step.

2. Use Wallet Address Reconstruction to Rebuild From the Chain

Public blockchains keep a permanent record of transfers. Wallet address reconstruction means taking every address you used, including exchange deposit and withdrawal addresses, and pulling the on-chain history for each from a block explorer or portfolio tool.

The chain shows dates, amounts and counterparties, not what you paid in dollars. Where you withdrew coins from an exchange to your own wallet, the chain shows the arrival even when the exchange's records are gone.

List every address you can find. One missed address leaves a hole.

The limitation: on-chain data covers transfers, not trades inside an exchange. Purchases made and sold within a closed account leave no public trail, and some activity is hard to read, such as bridges, swaps and smart contract interactions.

3. Match Transfers Between Your Own Wallets So They Are Not Treated as Sales

Once you have the history, label what is yours. Moving coins between your own wallets is generally a transfer, not a sale. If your software does not know both addresses are yours, it may read the outflow as a sale and the inflow as a purchase with no basis.

For each transfer, record the date, amount, both addresses and any network fee, and keep the lot's original purchase date and cost attached as it moves.

The limitation: pairing works when amounts and timing line up, and fees can make them differ slightly. Some transfers will stay ambiguous, so flag them instead of forcing a match.

4. Price Each Acquisition From a Documented Historical Source

With acquisitions identified by date and quantity, you need a price. Use a documented historical price source, record which one, and keep a copy or a screenshot of the figure with the date you pulled it.

Where you have a bank record showing what you paid, that amount is usually stronger evidence than a market price. A historical price for a day is an estimate, so label it as one.

The limitation: a historical price is not proof of what you paid. Do not assume any particular source or method will be accepted. We do not state that the IRS accepts any specific reconstruction method, and neither should your notes.

5. Document Your Missing Crypto Cost Basis Method and Gap With Your CPA

Some history will not come back. That is the honest outcome for many closed accounts. What you do with the gap matters more than hiding it.

Write a short memo: what you had, what you rebuilt, your price source, the transfers you matched, and the lots you could not support. Do not guess silently, because a number with no explanation is the hardest to defend.

Then ask a CPA how to document the gap for your facts and your tax year. Ask what to report for lots without support and what to keep.

The limitation: a memo does not turn an estimate into proof. Whether the treatment holds depends on your facts, and a CPA can tell you where your records are thin.

6. Set Up Records Going Forward: Per-Wallet Basis and the 1099-DA

Fix the cause. Export your history from every exchange you still use, on a schedule, because platforms close. Save the files somewhere you control and keep a labeled log of your own wallet addresses.

Basis tracking has moved toward a wallet-by-wallet or account-by-account view, so a record that treats everything as one pool may no longer fit. Brokers have also begun reporting digital asset sales on Form 1099-DA, with gross proceeds first and basis for some assets later. Confirm what applies to your tax year, since the phase-in has been adjusted.

A broker form sees only its own platform, so your own records still do the work.

The limitation: current-year records do not repair old gaps. They only keep a new one from forming.

Where Crypto Tax Made Easy Fits

Crypto Tax Made Easy is based in Little Silver, New Jersey, was founded in 2021 and has 6 employees. It serves clients nationwide, lists SMB owners, VC-backed startups, real estate investors and solopreneurs among its specialties, and states no revenue or income minimums.

Crypto Tax Made Easy has 6 verified client reviews on Sam's List as of 2026-10-02. Each review is submitted by an individual who identifies as a client of the firm and rates it on communication, subject-matter knowledge, and overall satisfaction. Reviews reflect those individual experiences and do not represent an endorsement by Sam's List. Crypto Tax Made Easy is a paid featured member of Sam's List. Ratings and rankings are not indicative of future performance or results.

The limitation, plainly: a six-person firm founded in 2021 has finite capacity and a short track record, and the profile does not say it offers record reconstruction. Ask whether it can work from on-chain data and partial exports, how it documents gaps, who prepares and who reviews, and what it charges.

Frequently Asked Questions

What can I do if my exchange closed and I cannot get my history?

Gather what outside records exist: old emails, bank and card statements, and any saved exports. Then use the blockchain to rebuild transfers by wallet address. Trades inside the closed account may not be recoverable. Document what you rebuilt and what you could not, and ask a CPA how to treat the gap.

Is a historical price from a website enough to support my basis?

It may help, but do not assume it is enough on its own. A taxpayer generally bears the burden of substantiating basis, and records generally should support figures on a return. A bank record of what you paid is usually stronger. Keep the source and date, label estimates, and ask your CPA.

Will transfers between my own wallets be taxed as sales?

Moving coins between wallets you own is generally a transfer, not a sale. The trouble is records: software that does not know both addresses are yours may read it as a sale and show zero basis on the other side. Match each transfer and keep the original lot details.

Should I guess my basis if I cannot find it?

Do not guess silently. A number with no explanation is hard to defend. Write down your method, your price source and the lots you could not support, then ask a CPA how to document the gap and what to report. Do not assume any reconstruction method will be accepted.

If you cannot say what you paid, start with step 1 this week and bring what you find to a CPA. You can browse accountants on Sam's List, including the firm above.

Methodology

This is a numbered list of steps in the order to do them, not a ranking of firms. The one firm written up is a vetted Sam's List member. Review counts come from the firm's Sam's List profile on the date shown, and each review reflects an individual client's experience.

Paid listings. Listing on Sam's List is free, and so is being named in this article. The firm written up here is a paid featured member of Sam's List, which is why it is written up here.

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About the author: Kimberly Green is cofounder of Sam’s List, a directory and matching platform for financial professionals.