BitMEX, BitMart, and AscendEX Are Shutting Down: Download Your Transaction Records Now

By Clinton Donnelly, LLM, EA | CEO & Founder, CryptoTaxAudit

Three crypto exchanges announced closures in July 2026. AscendEX halted operations on July 1 with almost no warning. BitMEX began winding down on July 23rd and will cease operations completely by September 23rd, 2026. BitMart ends all trading on August 26th, 2026, and shuts down for good on January 31st, 2027.

If you ever traded on any of these platforms, one task matters more than moving your coins: downloading your complete transaction history before your account access disappears.

Once an exchange goes dark, those records are gone. And without them, proving your cost basis to the IRS becomes significantly harder. That gap in your records can translate directly into overpaying taxes on gains you never actually made.

Key Takeaways

• Three exchanges are closing: AscendEX halted operations on July 1st, 2026. BitMEX ceases operations by September 23rd, 2026. BitMart ends trading on August 26th, 2026, and winds down fully by January 31st, 2027.
• Recordkeeping is legally your responsibility: Under tax code Section 6001, the taxpayer, not the exchange, is responsible for maintaining records that support the information reported on a tax return.
• Lost records create a cost basis hole: Without transaction history, you cannot prove what you paid for your coins. That gap follows you into every future sale of those assets.
• Missing records mean inflated gains: Crypto tax software with incomplete data will assign older, lower cost bases to your coins, showing profits that are higher than what you actually earned.
• The result is overpaying taxes: Higher reported gains mean a higher tax bill on profit that never existed. Downloading records now is the only reliable protection.

Which Exchanges Are Closing and When?

Three exchanges announced closures in July 2026, each on a different timeline. AscendEX (formerly BitMax) halted operations on July 1st, 2026, after losing its authorization under the EU's MiCA regulation, and formally announced the shutdown on July 6th. 

BitMEX began its closure process on July 23rd, 2026, and shut down completely on September 23, 2026, with assets left on the platform after that date subject to a $50 monthly maintenance fee or a 1% annualized levy. 

BitMart announced its wind-down on July 26th, 2026, discontinued all trading on August 26th, 2026, and plans to cease operations entirely on January 31st, 2027.

AscendEX users can still log in for limited functions, including exporting transaction histories. That window will not stay open forever.

The dates that matter to you are not the trading deadlines. They are the dates your login stops working. Once the platform shuts off account access, your transaction history is unrecoverable through normal means.

If you traded on any of these exchanges at any point, now or years ago, log in and export your records today. Do not wait for the final deadline. Exchanges in wind-down mode often reduce support staff and system reliability well before the official closure date.

Why Do Transaction Records Matter So Much for Taxes?

Your transaction records are the only proof of what you paid for your crypto, which is the foundation of every gain calculation you will ever file. When you sell a digital asset, your taxable gain is the sale price minus your cost basis. No records means no provable cost basis.

This matters even if you moved your coins off these exchanges years ago. Cost basis travels with the asset. Coins you bought on BitMart in 2021 and moved to a hardware wallet still carry that 2021 purchase price as their basis. The record of that purchase exists in exactly one place: BitMart's transaction history.

Gains are reported to the IRS on Form 8949. Every line on that form needs a cost basis you can defend. In an audit, the IRS can ask you to substantiate every number, and "the exchange shut down" is not an accepted excuse.

The Law Puts Recordkeeping on You, Not the Exchange

Tax code Section 6001 makes the maintenance of records the responsibility of the taxpayer. Not the exchange. Not the tax software. You.

This is a point many crypto traders get wrong. Exchanges are not required to preserve your data indefinitely or hand it to you after they close. When a platform winds down, its obligation to you effectively ends. Your obligation to the IRS does not.

In practice, this means a trader who loses access to their records has no legal fallback. If the IRS questions a cost basis figure and the taxpayer cannot produce documentation, the failure to keep records is treated as the taxpayer's fault. The burden of proof sits with you.

The practical takeaway: treat every exchange account like a filing cabinet you might lose access to at any time. Export your history regularly, and immediately when a closure is announced.

What Happens to Your Cost Basis Without Records?

A missing transaction history creates a hole in your ability to prove what your coins cost. That hole does not stay in the past. It affects every future tax year in which you sell, trade, or spend those assets.

Consider what happens without the records. You know you bought Bitcoin on one of these exchanges. You know roughly when. But you cannot document the purchase price, the date, the fees, or the amounts. When it comes time to calculate your gain, you have nothing to anchor the calculation to.

The IRS position on unsubstantiated cost basis is unforgiving. Without documentation, the IRS can treat your basis as zero, which makes the entire sale price taxable gain. A trader who bought $50,000 of crypto and sold it for $60,000 could end up taxed on $60,000 of gain instead of $10,000.

How Missing Records Inflate Your Tax Bill

Crypto tax software fills gaps in your data in ways that work against you. When online gain calculation tools are missing the purchase records from a closed exchange, they match your sales against older transactions with lower cost bases.

Here is the mechanism. Most tools use accounting methods that pull from your earliest available purchases. If your BitMEX buys are missing from the dataset, the software reaches back to older, cheaper acquisitions to assign a basis to the coins you sold. Lower basis means higher calculated profit.

The result is a gain figure that is simply wrong, and wrong in the government's favor. You pay tax on profit you never made, at amounts driven by prices you never actually paid. The software is not broken. It is doing the best it can with an incomplete record, and the incompleteness is invisible in the final report.

The only fix is complete data. Downloading your full history from these exchanges before they close is what keeps your gain calculation tied to what you actually paid.

What to Download Before Access Ends

Log in and export everything the exchange lets you export, in CSV format where available. At minimum, that means your complete trade history, deposit and withdrawal records, and any fee or funding statements the platform provides. Here is what that looks like on each closing exchange.

BitMEX: Log in, open your Wallet, go to transaction history, select all currencies and all transaction types for your full account lifetime, and download the CSV. Then export your trade and order history for every contract you traded, your realized P&L history, funding payment records, and deposit and withdrawal records. BitMEX closes its exchange services on September 23rd, 2026 at 04:00 UTC. Historical transaction information will remain accessible for a period after closure, but BitMEX is urging users to withdraw as soon as practical and has warned that withdrawal processing may slow.

BitMart: Trading stops August 26th, 2026 at 01:00 UTC, and BitMart urges users to submit withdrawal requests before 05:00 UTC that same day. Login access continues for a period after trading ends, but export your full trade history and deposit and withdrawal records now rather than testing how long that window lasts.

AscendEX: Do not send funds to any old AscendEX deposit address. Deposits are disabled and assets sent there risk permanent loss. Login still works for limited functions: export your deposit and withdrawal history, spot and derivatives trading records, and CSV account statements before submitting a withdrawal request. Withdrawals have been under manual review since July 6th and the exchange has said it cannot guarantee timing or amounts.

Three rules apply everywhere. Export from the first day you traded, not just recent activity, and run multiple date-range exports if the platform limits them. Verify every file opens and contains data before the exchange goes offline. Save copies in more than one place: your computer, a cloud drive, and an external backup. Screenshots of final balances are worth taking too.

If you have accounts on other exchanges, this is the moment to export those histories as well. The three closures announced in July 2026 will not be the last, and the pattern is always the same: short notice, then the records are gone.

Frequently Asked Questions About Exchange Shutdowns and Tax Records

Q: I traded on BitMEX years ago and moved everything off. Do I still need my records?

A: Yes. Cost basis travels with your coins. The purchase records from your old BitMEX trades are still the proof of what you paid, and you will need them whenever you sell those assets. Download the history before access ends, even if your balance there is zero.

Q: What happens if I can't prove my cost basis to the IRS?

A: Without documentation, the IRS can treat your cost basis as zero, making the entire sale price taxable gain. Under tax code Section 6001, keeping the records that support your return is your responsibility, so missing exchange data does not shift the burden off you.

Q: Will my crypto tax software just figure out the missing data?

A: No. Tax software with incomplete records will match your sales against older purchases with lower cost bases, which inflates your calculated gains. The software has no way to know a purchase is missing. It produces a confident number that is wrong in the government's favor.

Q: The exchange already closed and I never downloaded my records. What now?

A: Your options narrow considerably. Some records can be partially reconstructed from blockchain data, bank statements, and confirmation emails, but reconstruction is slower, more expensive, and less complete than a simple export would have been. Start gathering whatever secondary documentation you have.

Q: Should I wait until tax season to deal with this?

A: No. This is time-sensitive in a way tax work usually isn't. AscendEX has already closed, BitMEX ceases operations by September 23, 2026, and BitMart shuts down January 31, 2027. Once account access ends, the records are gone regardless of what tax season it is.

Q: Need help calculating gains with records from a closed exchange?

A: CryptoTaxAudit's gain calculation service specializes in building accurate, defensible cost basis records across exchanges, wallets, and chains, including situations where exchange data is incomplete.

About CryptoTaxAudit: Founded in 2015 by Clinton Donnelly (LLM, EA), CryptoTaxAudit specializes exclusively in cryptocurrency tax preparation and IRS audit defense. Clinton holds an advanced law degree in international financial planning, federal Enrolled Agent status, and the Certified Cryptoasset Anti-Financial Crime Specialist credential from ACAMS. The firm has filed more than 5,000 crypto tax returns, defended clients in over 50 IRS audits, and represented five traders in U.S. Tax Court. The firm's crypto analytics team routinely reconstructs trading histories and cost basis records, including for accounts on exchanges that no longer exist.

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