Hacked tokens, bankrupt platform: what to tell the tax authorities?

The rule that governs everything

For private wealth, capital gains are tax-exempt and, in return, losses are not deductible. Neither a hack, nor a platform bankruptcy, nor a lost key reduces your income tax. That is the price of the exemption, and there is no exception for unfortunate circumstances.

What an incident changes is your declaration of wealth, which is based on the situation at the end of the tax period. So the question is never “can I deduct my loss?”, but “what exactly did I own on 31 December, and at what value?”.

There is one exception: if you are classified as a professional securities trader, your gains become taxable and your losses deductible. You do not choose this status: it is established from the facts.

Declaring an uncertain claim, in practice

This is the trickiest case, and the one readers most often get wrong. A claim is not declared at its nominal amount if it is clearly not worth that amount, but it does not disappear from your wealth either just because recovery is doubtful.

1. Establish the nominal amount. The value of your holdings when the bankruptcy was opened, converted into francs. This is the starting point, not the amount to declare.
2. File your claim with the liquidator, within the announced deadline. Without filing, you no longer have any claim at all, and no way of justifying a reduced value.
3. Look for a figure. The liquidator's communications, a projected dividend, the schedule of claims, a distribution plan. This is what turns an estimate into a valuation.
4. Use a reasoned value, and enclose an explanatory note of a few lines: the origin of the claim, the ongoing proceedings, the recovery rate used and its source.
5. Adjust it every year for as long as the proceedings last. An international bankruptcy can go on for years, and the value of the claim changes with it.

If no figure is available, say so in your note rather than putting forward an invented number. An administration readily accepts a prudent, documented valuation; it does not accept an unexplained amount.

Three points that change the outcome

A Swiss platform is not a foreign platform. If a platform established in Switzerland goes bankrupt and your crypto-assets were held there in a way that allows them to be individually identified, the law allows them to be segregated from the bankruptcy estate: you remain their owner and declare them at the year-end price, as if nothing had happened. This possibility comes under Swiss debt enforcement law and does not help you with proceedings opened abroad, which is the case for the vast majority of platforms.

A reimbursement is not income. If a protection fund or a liquidator pays you compensation, the payment replaces capital you already owned. It is not taxable income. Any interest paid on top is another matter, and it has not been settled: put it to your cantonal administration.

A hacked personal wallet is treated differently. If it is your own keys that were compromised and your tokens transferred, you no longer own anything: they simply leave your wealth as at 31 December. There is no claim to value and no loss to deduct. Nevertheless, keep a record of the incident (destination address, date, any criminal complaint filed), because the disappearance of a large amount from your successive tax returns calls for an explanation.

What to do on the day

Everything above assumes you can prove what you held. Platforms in difficulty close their interfaces, switch off exports, and sometimes disappear. What you do not capture in the first few hours is often lost.

1. Capture your balances, with the date visible on screen.
2. Export the complete history of your transactions, while the function is still available.
3. Keep the official announcement of the suspension or bankruptcy, with its date.
4. Note, for each currency concerned, the quantity and the price on the day. Without these three elements, you will be able to quantify neither a loss nor a reimbursement.
5. Ignore recovery services. Nobody unblocks funds in exchange for payment. These offers are almost always a second scam.

Find out more

The guide Understand sets out the basic rules in thirty-three pages: wealth, income, and the boundary with professional activity. It is free.

This page grew out of the newsletter of 30 September 2026 on the Bitget hack, which you can read here.