What happens if your crypto went unreported?

The obligation to report does not expire

Disposals of crypto assets have always been taxable and reportable. A disposal does not only mean selling for euros. According to the Tax Administration, exchanging crypto assets for other crypto assets is also a taxable event, as is paying with crypto assets. Exchanges are exactly what most people overlook: there are many times more transactions than they remember making.

The end of a tax year does not remove the obligation. It only changes how the omission is corrected and what the consequence is.

The consequence depends on timing

In euros, the difference between a self-initiated correction and one detected by the Tax Administration can be small. What matters more is that the harsher category is only decided once the Tax Administration steps in itself – and by then the initiative is no longer yours.

Deliberate tax avoidance may meet the definition of tax fraud. This page covers the ordinary situation where returns have gone unfiled because of unawareness or messy records. If the Tax Administration has already contacted you, say so in the diagnosis and mention the deadline.

Why timing matters more now

From the start of 2026, crypto service providers have been required to collect their customers' identification and transaction data for reporting to the Tax Administration. Data for 2026 will reach the Tax Administration during 2027, including from foreign providers. Your obligation has not changed. What has changed is that the information will now travel without you as well. Read more: CARF and DAC8 – what they mean for Finnish residents.

According to the Tax Administration, there are an estimated 300 000 crypto asset owners in Finland, yet only around 8 200 people reported crypto trades for tax year 2023. That gap is what the reporting will narrow.

What a correction takes in practice

1. All years and all sources. Every exchange account, every wallet, every chain. Correcting a single year is not enough, because acquisition costs of crypto carry over from year to year: a purchase in 2021 affects the gain on a sale in 2024.
2. Acquisition costs. The Tax Administration applies the FIFO principle: crypto assets are deemed used in the order they were acquired, unless shown otherwise. If a purchase cannot be demonstrated, the deduction is limited to the deemed acquisition cost – 20 % of the sale price, or 40 % if the asset has been held for at least ten years. That is almost always clearly worse than the actual acquisition cost.
3. Losses. Capital losses are deducted first from capital gains of the same year and then from other capital income, and any unused part can be used in the following five tax years. Correcting an old year can therefore also reduce this year's tax.
4. Reporting in MyTax (OmaVero). Before the assessment is closed, you correct the details on your tax return. A closed assessment is corrected by filing a claim for adjustment (oikaisuvaatimus). See the deadlines: Can you amend an old tax return?

When your own calculation does not reconcile

For most people, a correction fails on the records, not on the tax rules. The exchange export is incomplete, some wallets have been forgotten, and the calculator shows sales with no matching purchase. The typical causes and how to spot them are collected in the guide Why your crypto tax calculator cannot make your history reconcile.