Mercado Bitcoin Hack: Accounting Steps After a Withdrawal Halt

CryptaCount Editorial · November 3, 2026 · 6 min read

Mercado Bitcoin, described as Brazil's largest crypto exchange, has halted withdrawals after a hack reported at $40 million. For accounting firms, auditors and CFOs with Brazilian exchange exposure, the so-what is immediate: balances held there may no longer be freely available, and that changes how they are classified, measured and disclosed. Reliable crypto accounting software that preserves a clean, time-stamped record of positions is what makes that exercise defensible.

A caveat first. The only confirmed facts available to us are the headline-level ones: the exchange, the withdrawal halt, and the reported $40 million loss. We do not have the exchange's own statement, the attack method, the affected assets, any regulator response or a restart timeline, so this article does not speculate on them. What follows is analysis of what a withdrawal freeze generally means for the books, and what to check as official information emerges.

What is confirmed and what is not

The reported facts

Per the report, the exchange suspended withdrawals following a hack with losses of about $40 million. That is the full extent of what we can state. The report does not, in the material available to us, tell us whether customer assets, the exchange's own reserves, or both were hit, nor whether customers will be made whole.

The open questions that drive the accounting

Each unknown maps to a different accounting outcome. Whether losses fall on the exchange's balance sheet or on customers decides if a client's claim is a full receivable or an impaired one. The length of the halt decides whether balances are better treated as temporarily restricted or as a credit exposure to a counterparty in distress. Until the exchange or a regulator publishes details, firms should document these as unresolved rather than assume a benign outcome.

Accounting implications for firms and CFOs

Classification of balances held on the exchange

Crypto sitting in an exchange account is an asset held through a custodian. When withdrawals are frozen, the practical question is whether the entity still controls the asset or merely holds a claim on the exchange. Management should record its judgement, the evidence behind it, and the date it was made. Where a client's own policy treats exchange balances as digital assets held, the freeze is a trigger to revisit that policy for this counterparty.

Impairment, measurement and subsequent events

If the reporting date falls before the halt but the financial statements are not yet issued, the event may need evaluation as a subsequent event, and the nature of the evaluation depends on the framework the client reports under. If the date falls after, consider whether recoverability of the balance is in doubt and whether a loss allowance or write-down is appropriate. These are judgement calls that should rest on facts from the exchange, not on press reports alone, so keep a log of what was known and when.

Disclosure and going-concern angles

Entities with a material share of liquidity on the exchange should consider disclosing the concentration, the restriction on access and the uncertainty over recovery. For clients that relied on those funds to meet near-term obligations, liquidity and going-concern assessments may need to be refreshed. Auditors should expect to be asked for confirmations and should plan for the possibility that the exchange cannot respond quickly.

Records, reconciliation and tooling

Freeze a clean position snapshot

The first practical step is a dated snapshot of every wallet and account balance tied to the exchange, reconciled to the last trade, deposit and withdrawal records. Good digital asset accounting software lets you lock a period, export a transaction-level ledger and show exactly which entries relate to this venue. If your bookkeeping runs through crypto bookkeeping software, confirm that exchange API imports are complete up to the halt and that any pending withdrawals are flagged rather than booked as settled.

Pending and in-flight transactions

A withdrawal requested before the halt but not completed is a classic cut-off problem. Treat it as unsettled until you can see it on-chain at your own address. Likewise, do not recognise a loss or a recovery on the strength of rumours. Record only what you can evidence.

Chain-level evidence

Where the exchange or analysts later publish theft addresses, matching your own deposit history against them helps show which flows predate the incident. We have not seen such addresses in the material available, so none are cited here.

Tax and AML considerations

For firms and corporate clients

Whether a loss from an exchange hack is deductible, and when, depends on local rules and on facts not yet known, including whether the loss is final or recoverable. For Brazilian taxpayers, the treatment should be confirmed against the guidance of the Receita Federal and with local advisers before any position is taken. Do not assume a write-off is available simply because funds are inaccessible. Keep evidence of the original acquisition cost, because you will need it under any outcome.

For individual filers

If you hold coins there, you are probably wondering whether you owe tax on anything. A freeze on its own is not a sale, so it does not by itself create a gain. Don't file a loss yet. Save your account statements, trade history and any emails from the exchange, and wait for official word on recovery. If you later receive a partial payout or replacement assets, how that is taxed will need separate analysis.

AML and counterparty due diligence

Hacks of this kind raise the usual questions around tracing stolen funds and onward laundering. Firms with Brazilian exposure should also consider the wider licensing context, which we covered in our piece on the Brazil crypto licence deadline and compliance risk. Revisit your counterparty due diligence file for this exchange and record any change in risk rating.

Practical next steps

A short checklist

Snapshot and reconcile all balances and transactions linked to the exchange.
Record the date you learned of the halt and your assessment of control over the assets.
Evaluate subsequent-event, impairment and disclosure questions against your reporting framework.
Refresh liquidity forecasts for clients with material funds on the platform.
Monitor the exchange's official communications and any regulator statements, and update your file as facts firm up.

For how a comparable withdrawal suspension was handled in the books, see our analysis of the Binance hack and withdrawal suspension. For wider compliance context, start with our crypto compliance reporting guide.

FAQ

Does a withdrawal halt mean I must write off my balance?

Not automatically. A freeze raises a recoverability question, and the answer depends on facts not yet public. Document your judgement and revisit it as official information arrives.

Can I deduct the loss on my Brazilian tax return?

We cannot say. Deductibility depends on local rules and on whether the loss is final. Check Receita Federal guidance and consult a local adviser before taking a position.