Declaring Crypto Taxes in Sweden 2026 — K4 Step by Step

Declaring crypto to Skatteverket has gone from “should do” to “must do right”. Since January 1, 2026, the EU’s reporting rules (DAC8) are in force: crypto exchanges are required to share their customers’ transaction data with tax authorities. In other words, Skatteverket already sees more than most people think. In this guide we walk through exactly how to declare crypto in Sweden — the K4 form, the average cost method, the 70% loss rule and the most common mistakes.

New in 2026: Skatteverket sees your transactions

DAC8 — the EU’s crypto-asset reporting directive — took effect on January 1, 2026. In practice it means exchanges with EU customers must report their clients’ holdings and transactions to tax authorities, who share the data between countries.

The conclusion is simple: the “they can’t see it anyway” strategy is dead. If you have undeclared previous years, correcting voluntarily is the smart move — a self-correction normally carries no penalty surcharge, while being discovered later can get expensive.

What is taxable?

Taxable events (capital gains, 30%):

• Selling crypto for kronor or any fiat currency
• Swapping one crypto for another — yes, including into stablecoins
• Paying for goods or services with crypto

Taxed as interest income (30%): staking and lending rewards are declared as interest.

NOT taxable: moving crypto between your own wallets and accounts, receiving gifts, or simply holding. Migrating from one exchange to another — for example away from Binance after the EU lockout — triggers no tax by itself. But if you sell along the way, that is a disposal.

The maths: the average cost method

Skatteverket requires the average cost method (genomsnittsmetoden) for crypto. The principle:

Gain/loss = sale price − cost basis

Your cost basis is the average acquisition price for that specific cryptocurrency, in SEK, across all your purchases — regardless of exchange or wallet. Bought 0.1 BTC at 50,000 kr and later 0.1 BTC at 70,000 kr? Your average is 600,000 kr/BTC, and any sale is measured against that average.

Filling in the K4 form

• 1. Crypto is reported on form K4, section D (“Other securities, other assets”) — found under attachments in the e-service.
• 2. Report per cryptocurrency: quantity, total sale price and cost basis.
• 3. Report gains and losses separately — do not net them yourself; the form applies the 70% rule.
• 4. Staking/lending rewards: declared as interest income (box 7.2), not on the K4.
• 5. The declaration is filed in spring — the deadline is normally in early May (2026: May 4).

Losses — the 70% rule

Crypto losses are deductible at 70 percent against capital gains. Example: a 10,000 kr gain on one coin and a 10,000 kr loss on another does not net to zero — it nets to 10,000 − 7,000 = 3,000 kr of taxable gain.

That makes two things important: report your losses (many forget — it is money), and mind the asymmetry before “selling and buying back” to tidy the portfolio. Every round trip through fiat or stablecoins locks in 30% tax on gains but only a 70% deduction on losses.

Most common mistakes

• Crypto-to-crypto swaps — by far the most common miss. Every swap is a disposal, including BTC→ETH and including into USDC.
• Lost history — transactions on defunct exchanges or old wallets. Export your history in time (especially from exchanges you are leaving).
• Staking on the K4 — rewards are interest income, not capital gains.
• No documentation — keep transaction exports and price data. If Skatteverket asks, the burden of proof is in practice yours.
• Not declaring at all — with DAC8 that is no longer a risk, it is a countdown.

The basics of Swedish crypto taxation — rates, examples and different situations — are covered in our overview of crypto tax in Sweden. And if you trade actively: an exchange with proper export functions makes declaration season far easier — see our Kraken review.

Frequently asked questions