Losses from earlier years

A stock-market loss: five years, but never more than half a year

A loss is deducted from later years’ profit. Two limits decide how much you actually deduct this year — and both are measured against the year the loss arose.

What the statute says

Five years, counted from the year after: Art. 9 ust. 3 ustawy o PIT. A loss from 2021 can reduce income for 2022–2026. In 2027 it lapses — no application, no notice.
No more than half in a single year: The cap is measured against the ORIGINAL size of that year’s loss, not against what is left. A 10 000 zł loss means at most 5 000 zł a year — even against a far larger profit.
Only within the same source: A loss on shares reduces a gain on shares. Crypto losses cannot be added to it — art. 30b ust. 5a keeps them apart.

How we compute it

Year by year, oldest first: The loss that expires soonest is used first. The other order would let the older one lapse unused.
We keep the split by source year: Not one figure “X used”, but how much came from each year. Without it, next year’s half-cap would be computed against the wrong base.
Recomputing a year replaces, never adds: You add a forgotten statement and compute the year again — the previous deduction is replaced. Otherwise the first correction would eat the loss twice.

Where people get it wrong

The half-cap taken against the remainder: A 10 000 zł loss, 5 000 deducted last year. 5 000 remains — and people deduct half of that, 2 500. The full 5 000 is allowed: the half is measured against the original 10 000.
A loss declared without the year it arose: Without the year, neither the five-year window nor the cap can be checked. The office may reject the whole deduction, not merely the excess.
A crypto loss filed in section C/D: It looks like the same loss, but it belongs to section E/F under different rules — no five years there, and no half-cap.
The loss-making year never filed: A return for a year with nothing but a loss feels pointless. Without it there is nothing to carry: a loss exists once it has been declared.

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claude mcp add --transport http taxroam https://taxroam.com/mcp --header "Authorization: Bearer $TAXROAM_KEY"

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Questions about losses

My loss is larger than this year’s profit. What happens to the rest?

It stays for later years, up to five from the year it arose. This year’s tax is zero and the remainder waits.

Must I deduct the loss at the earliest opportunity?

There is no such duty, but waiting costs: an undeducted loss lapses for good after five years.

Where will you get last year’s loss from?

From the calculation you ran with us — we keep yearly sums only, never transactions. If that year was computed elsewhere, you give the amount and the year yourself.