Foreign‑Currency Cash Accounts vs. Forex‑Pair Trading

Do I file anything if my USD balance never reaches 0 and withdrawals don't exceed costs?

For a foreign-currency cash account (foreign-currency cash account), you only declare on form K4 in the year a taxable gain or deductible loss actually arises. This happens if:

• Your withdrawals (valued in SEK) exceed your total accumulated SEK acquisition cost, or
• You empty the account while some SEK acquisition cost remains unused (this remaining cost becomes a deductible loss).

If neither of these occurs in a tax year, you don't need to declare anything for that currency account that year, even if you made deposits or withdrawals. Keep your ledger updated.

Skatteverket says (Swedish):
"Beskattning av vinst eller avdrag för förlust sker inte förrän fordrans totala omkostnadsbelopp har utnyttjats."

English translation:"Tax on a gain—or deduction for a loss—is triggered only after the claim's entire acquisition cost has been consumed."

What FX rate (växlingskurs) do I use?

Skatteverket provides the following hierarchy for determining the exchange rate:

• Actual exchange rate: If you exchanged currency on the acquisition or disposal date.
• 30-day rule: The actual exchange rate also applies if you exchange the sale proceeds into SEK within 30 days of the disposal date.
• Riksbanken's mid-rate: If no actual exchange occurred as per the above, use the Riksbanken's daily published mid-rate for the transaction date.
• Average of buy/sell rates: If Riksbanken does not provide a mid-rate for the currency on that day, use the average of the day's official buy and sell rates.

Skatteverket says (Swedish) regarding exchange rates:
"Om du har växlat på förvärvs- eller avyttringsdagen används den faktiska växlingskursen vid kapitalvinst­beräkningen. Detsamma gäller om du växlar försäljnings­intäkten inom 30 dagar från avyttringsdagen. Om du inte har växlat bör du använda den så kallade mittkursen som Riksbanken publicerar varje dag. Saknas mittkurser … kan du ta ett genomsnitt av transaktionsdagens köp- och säljkurser."

English translation:
"If you exchanged currency on the acquisition or disposal date, the actual exchange rate is used in the capital-gain calculation. The same applies if you exchange the sale proceeds within 30 days of the disposal date. If no exchange has occurred, you should use the Riksbank's daily mid-rate; if no mid-rate exists for that currency, use the average of the day's official buy and sell rates."

How are losses on foreign currency accounts handled (förlustavdrag)?

If you have a loss on a foreign-currency cash account (which is considered a fordran or claim), its deductibility depends on whether the claim is market-listed:

• Market-listed foreign-currency claim: Losses are 100% deductible.
• Non-market-listed foreign-currency claim: Losses are generally 70% deductible (according to 48 kap. 24 § IL).

Most retail currency accounts held with brokers are considered market-listed.

Skatteverket says (Swedish) regarding losses on market-listed claims:
"Skatteverket anser att förlust på en marknadsnoterad fordran i utländsk valuta ska vara avdragsgill till hundra procent."

English translation:
"The Tax Agency holds that a loss on a market-listed claim in foreign currency is 100 percent deductible."

What is the 30-day rule (30-dagarsregeln) for currency conversion?

The 30-day rule is a specific provision in Swedish tax law (primarily from 44 kap. 16 § Income Tax Act - Inkomstskattelagen) that simplifies tax calculation when you sell an asset (like shares or property) and receive payment in foreign currency, provided you convert those specific sale proceeds into SEK within 30 days of the sale (avyttringsdagen).

How it works:

• Instead of multiple calculations, if you meet the 30-day condition, you can use the actual SEK amount you received from the currency exchange as the official sales proceeds for the original asset.
• This effectively bundles any currency gain or loss on the sale proceeds directly into the capital gain/loss calculation for the asset itself.

What if the 30-day rule is not applied?

If you don't convert the foreign currency proceeds to SEK within 30 days, or if you, for example, deposit them into your regular foreign-currency cash account (foreign-currency cash account) to hold, the simplification does not apply. You would then typically need to perform separate calculations:

1. Calculate the gain/loss on the sold asset (e.g., shares) by converting the foreign currency sale price to SEK using the exchange rate on the sale date.
2. The foreign currency amount received is then considered a separate claim (en fordran i utländsk valuta, often called a "köpeskillingsfordran" if it represents unsettled payment for a sale). If this claim is held before being converted or used, its value can fluctuate.
3. When this currency is later converted to SEK or used (e.g., withdrawn from a foreign-currency cash account), any gain or loss on the currency itself (from the time it was acquired as sale proceeds to the time it was converted/used) is calculated based on the rules for that type of holding (e.g., the cost recovery method for a foreign-currency cash account).

Important: The 30-day rule is specifically for the proceeds from selling another asset. It does not change how you calculate gains/losses on a general foreign-currency cash account (foreign-currency cash account) balance that accumulates from various sources or is held for longer periods.

Skatteverket guidance (referring to 44 kap. 16 § IL):
(Swedish excerpt from Skatteverket typically explains that if proceeds from a sale are exchanged to SEK within 30 days, that actual SEK amount can be used as the sale price for the original asset.)
"Om du har växlat på förvärvs- eller avyttringsdagen används den faktiska växlingskursen vid kapitalvinst­beräkningen. Detsamma gäller om du växlar försäljnings­intäkten inom 30 dagar från avyttringsdagen."

English translation of the core idea:
"If you exchanged currency on the acquisition or disposal date, the actual exchange rate is used in the capital-gain calculation. The same applies if you exchange the sale proceeds within 30 days of the disposal date."

(This quote is also found in Skatteverket's general guidance on FX rates for capital gains, like on their page about "Utländsk valuta" or "Valutahandel").

For detailed rules, refer to Skatteverket's official guidance on "Beskattning av tillgång mot ersättning i utländsk valuta" or the Income Tax Act itself.