Forex loss in tax return — how to file

A forex loss hurts, but properly filed it becomes a tax asset you can use for five more years under Polish law. The PIT-38 return turns it into a real deduction against future capital-gains income, thanks to article 9 paragraph 3 of the Personal Income Tax Act. Two rules govern the process — a five-year window and a fifty-percent annual cap — and both surprise traders who only think about taxes after the fact. Here is how the mechanism actually works, with a worked example using a Polish broker and Polish zloty.

Is a forex loss tax-deductible in Poland

Yes. Polish tax law treats profit and loss from CFD trading on currency pairs as income from capital sources, the same bucket that holds shares, ETFs and crypto. You report all of it on a single annual return called PIT-38, with a flat 19 percent rate on net gains (the so-called Belka tax). If the bucket ends the year in the red, you can carry the loss into the future.

Three rules to memorize before your first filing:

• Five consecutive tax years to use the loss, counted from the year after it was incurred. A loss from 2024 expires after the 2029 filing season.
• At most 50 percent of the loss amount from one given year can be deducted in any single later year. Whatever is left carries forward inside the same five-year window.
• Within the same income source only. A forex loss can only reduce later capital-source gains. It will not offset salary, freelance fees, or rental income from a separate source.

Contrary to a common piece of advice on Polish trading forums, simply reporting the loss costs nothing — the tax office will not refund tax against a loss. The paper trail matters because it is the only thing that gives you the right to deduct later. Skip the PIT-38 in a loss year and you have nothing to carry forward, regardless of how profitable the next year turns out.

How the fifty-percent cap works in practice

Illustrative example, not tax advice. Suppose Marta — an independent trader using a Polish broker — closed 2024 with a 20,000 PLN net loss on EUR/USD and GBP/JPY pairs. In 2025 she recovered and made 8,000 PLN net of platform fees. Without carryforward she would owe 19 percent on that gain, namely 1,520 PLN. With the loss applied, the math looks different.

There is a subtlety worth pinning down. The fifty-percent ceiling refers to the original loss amount, not the balance you still have. That is why Marta could deduct 10,000 PLN in 2027 even though only 6,000 PLN of the loss remained. For a much larger figure, say 100,000 PLN, the shortest possible path to a full write-off is two years at 50,000 PLN each — assuming both years bring sufficient gains. In reality, with annual gains of 10,000 to 20,000 PLN, a large loss can simply expire before being fully recovered.

Filling in PIT-38 with a loss step by step

The mechanics, whether you use the Twoj e-PIT pre-filled portal or work through the paper form yourself:

1. Gather broker documents. Polish brokers such as XTB, BOS, mBank Brokerage and DM BPS send a PIT-8C form automatically by the end of February, listing total revenue, total cost, and the year-end result. Foreign brokers operating without a Polish registration (IC Markets, Pepperstone, Interactive Brokers) do not issue PIT-8C, so you build the calculation yourself from the annual statement.
2. Fill in parts C and D of the PIT-38 — capital-source revenue and costs. For a foreign broker, translate trade results to PLN using the average NBP rate from the day before each transaction.
3. Part E is where the loss lives. If costs exceed revenue, the negative balance goes here. This entry creates the right to deduct in the next five years.
4. On the following year's return, if you have a gain, return to part E and enter the deduction. Remember the cap of fifty percent of the original loss, and that the deduction cannot exceed the current year's capital-source income.
5. File by 30 April — the simplest route is Twoj e-PIT, which pre-fills the form with PIT-8C data. Not filing a return in a loss year forfeits the carry-forward right.
6. Keep documents for five years from the end of the year in which the payment deadline fell. PIT-8C, the broker's annual statement, a trade ledger and account statements are the minimum if the tax office requests an audit.

One observation from watching the retail-trading market in Poland: small losses of one or two thousand zloty per year usually are not worth the bookkeeping if you do not plan to trade consistently. Larger ones — from around ten thousand upwards — should be reported without exception, because skipping them means giving up the right to offset future gains. The PIT-38 overview covers the rest of the return, and deductible costs explains what counts as a cost reducing your tax base. For wider context on record-keeping and reporting duties across jurisdictions, the ForexMechanics taxes and records section is a useful supplement.

What if you forgot to report a loss in a prior year

This is more common than you might think: a trader closes the year in the red, decides that no tax owed equals no return required, and finds out about the gap only when the next year ends in profit. The fix is a corrective filing — a PIT-38 marked as a correction — for the loss year. You can submit it until the statute of limitations runs out, namely five years from the end of the year in which the payment deadline fell. Alongside the correction it is worth filing a so-called czynny zal, a voluntary disclosure under the Polish fiscal penal code that mitigates any potential sanction.

The correction itself does not trigger a penalty if your earlier omission did not understate any tax due. In a loss year you simply file the missing return and recover the right to carry forward. That separates Poland from jurisdictions where missing the deadline closes the door permanently.

„O wysokość straty, o której mowa w ust. 2, poniesionej w roku podatkowym podatnik może obniżyć dochód uzyskany z tego źródła w najbliższych kolejno po sobie następujących pięciu latach podatkowych, z tym że kwota obniżenia w którymkolwiek z tych lat nie może przekroczyć 50% wysokości tej straty." — Ustawa o podatku dochodowym od osob fizycznych, art. 9 ust. 3, Dz.U. 1991 Nr 80 poz. 350 (consolidated text, 2026)

Common mistakes and interpretive traps

Four things most often spoil loss filings for Polish retail forex traders:

• Mixing sources. A forex loss will not reduce tax on a real-estate sale or business income — only future capital-source gains. If you want to trade inside a company, a different regime applies, as the forex as a company article explains.
• Counting the cap against the balance, not the original amount. The fifty-percent ceiling refers to the same number every year — the loss as originally reported. Two partial deductions do not shrink the ceiling.
• Omitting costs from a foreign broker. Spreads, swaps and account fees are deductible costs of generating revenue. Skip them and the reported loss will be smaller than the real one.
• Assuming no PIT-8C means no obligation. If your broker does not issue the form, you still have to report the result. The platform's annual statement plus an NBP-rate-based translation to PLN is enough evidence.

What to do tomorrow

1. Log into your broker's portal and download annual transaction statements for the last five years — this is the foundation for checking whether any closed year was a loss you never declared. Without these statements, no honest calculation of what is still available to deduct is possible.
2. Open every PIT-38 you filed in the last five years (they are stored in the Twoj e-PIT service) and look at part E — write down on paper how much loss is still available to use from each origin year. The fifty-percent ceiling is calculated against the original amount, not the running balance.
3. Decide which of the upcoming years should host the largest deduction — savings are biggest in years with high capital-source income, so it can pay to wait one year and apply the loss against a larger gain rather than spending the ceiling on a small result.
4. If you missed reporting a loss in a previous year, prepare a corrective PIT-38 together with the so-called czynny zal — both are formalities, but they require written form and concrete reasoning, so do not leave them for the deadline day.
5. Book a session with a Polish tax adviser (typically 200 to 400 PLN) if your loss exceeds about fifteen thousand zloty, or if you traded with a broker outside the European Union — both cases bring details that affect the deductible amount more than the basic filing duty.