A loss is worth something — but only for five years
A bad year on the stock market doesn't just hurt. It also gives you something: a loss you can use to cut your tax on gains in the next five years.
The catch is that nothing happens on its own. The tax office doesn't carry the loss across for you, and the rules on how much you can deduct each year are stricter than most people expect. This guide walks through them one step at a time.
If you invest in crypto, this article isn't for you. Crypto has no "loss" at all — it has excess costs, and the rules are far more generous. See Crypto losses: it's not a loss, it's a cost.
Step 1: the loss year — field 29
A loss arises in Part C of the form when your total costs (field 27) are higher than your total revenue (field 26). You then put the difference in field 29 (loss) and leave field 28 (income) at 0.
That's all you do in the loss year. There's no tax to pay, but you still have to file the return. The Ministry of Finance brochure only lets you deduct losses that taxpayers "reported" for earlier years. If you skip filing in the bad year, there's no loss on record to deduct later.
What the law says
Field 30 is in Part D. According to the brochure, in the 2025 return you can deduct losses from 2020–2024 on:
- selling securities (shares, ETFs, bonds) and exercising rights attached to them,
- short selling (selling borrowed securities),
- selling derivatives and exercising rights attached to them,
- selling shares in companies or in a cooperative,
- taking up shares in exchange for a non-cash contribution.
There's one exception for investment fund units (redeeming or buying back units of an investment fund): there, the brochure only allows losses from 2024.
How much you can deduct comes from art. 9(3) of the PIT Act. You choose one of two methods:
| Method 1: the 50% rule | Method 2: one-off deduction | |
|---|---|---|
| How it works | Deduct in each of the next 5 years | Deduct once, in any one of the next 5 years |
| Limit in a single year | 50% of the loss | Up to 5,000,000 PLN |
| What's left over | Carries to the remaining years, max 50% per year | Carries to the remaining years, max 50% per year |
And one limit applies to both methods: field 30 can never be more than field 28. You can only deduct a loss from income you actually have. A loss can't create a refund or turn your income negative.
The one-off deduction isn't just for millionaires
The 5 million PLN cap makes method 2 sound like it's for large investors. In fact it works the other way round. For almost any retail investor the whole loss is below 5 million, so method 2 simply means: deduct as much as your income allows, all at once, without the 50% cap.
The five years run out
Each loss has its own five-year window, starting the year after the loss.
| Loss from | Last return you can deduct it in |
|---|---|
| 2020 | 2025 (filed in 2026) |
| 2021 | 2026 |
| 2022 | 2027 |
| 2023 | 2028 |
| 2024 | 2029 |
The return for 2025 is your last chance to use a loss from 2020. Whatever isn't deducted by then is gone.
If you have losses from several years, track each one separately — with its own amount, its own 50% cap and its own expiry date. On the form, field 30 shows only the total you're deducting this year.
A worked example, step by step
In 2024 you sold an ETF at a loss. Your 2024 return showed 30,000 PLN in field 29.
In 2025 things went better: you made 20,000 PLN of income from selling shares (field 28).
Method 1: the 50% rule
| Field | What it is | Amount |
|---|---|---|
| 28 | Income in 2025 | 20,000 |
| 30 | Loss deducted (max 50% × 30,000) | 15,000 |
| 31 | Tax base: 20,000 − 15,000 | 5,000 |
| 33 | Tax: 5,000 × 19% | 950 |
Left to deduct later: 15,000 PLN, in 2026–2029.
Method 2: one-off deduction
| Field | What it is | Amount |
|---|---|---|
| 28 | Income in 2025 | 20,000 |
| 30 | Loss deducted (no 50% cap, but no more than field 28) | 20,000 |
| 31 | Tax base | 0 |
| 33 | Tax | 0 |
Left to deduct later: 10,000 PLN, in 2026–2029 — but now at most 15,000 per year (50% of the original loss).
What the choice was worth
Method 2 saves 950 PLN this year. The total amount of loss is the same either way — method 2 just lets you use it sooner. Using it sooner also means less risk of it expiring unused if your next few years are quiet.
Keep in mind that the one-off deduction is one-off: you can use it only once for a given loss. After that, every remaining year is back to the 50% cap.
Losses stay in their own bucket
A loss on shares reduces only income from Part C — sales of shares, ETFs, bonds, derivatives and fund units. It can't reduce:
- crypto income (Part E) — that's a separate bucket with its own cost rules,
- dividends or interest (Part G) — those are taxed at a flat rate with nothing deducted,
- your salary or business income.
The same goes the other way: excess crypto costs won't help with a stock gain. More on the two buckets in What can you deduct in PIT-38?.
Exactly where these numbers go
| Field | What goes there |
|---|---|
| 29 | The loss, in the year it happened (Part C) |
| 30 | Losses from 2020–2024 deducted this year — never more than field 28 (Part D) |
| 31 | Field 28 minus field 30, rounded to whole złoty |
| 32 | Rate: 19% |
| 33 | Field 31 × 19% |
The tax base in field 31 is rounded to whole złoty: amounts under 50 groszy are dropped, 50 groszy and over round up.
Common mistakes
- Not filing in the loss year. "I made no money, so there's nothing to file." There is: without field 29 on a filed return, the loss doesn't exist as far as the tax office is concerned.
- Deducting 100% under method 1. The 50% rule caps each year at half of the original loss, not half of what's left.
- Putting more in field 30 than in field 28. The excess doesn't carry over as a bigger loss — it's simply not allowed.
- Using a stock loss against crypto. Different part of the form, different bucket.
- Forgetting the expiry date. A 2020 loss can't be used after the 2025 return.
- Mixing up loss years. Keep a small table: year, original amount, deducted so far, what's left, expiry.
Before you file
- Did you file a return in each loss year, with the amount in field 29?
- Do you have those returns (or their UPO confirmations) to hand?
- Have you chosen a method for each loss — the 50% rule or a one-off deduction?
- Is field 30 no higher than field 28?
- Are any of your losses from 2020? This is the last year to use them.
- Have you updated your tracking table with what's left for next year?
The return for 2025 is filed between 15 February and 30 April 2026.
This article is educational and is based on the Ministry of Finance information brochure for the PIT-38 return for 2025 and on art. 9(3) of the PIT Act. It is not tax advice.