Dopłata przysługuje, o ile potrącenie było błędem.

Dopłata means an additional payment, top-up, or extra amount that is due. In official or administrative language, it often refers to money that should be paid to make up for an earlier shortfall.

Grammatically, dopłata is a feminine noun in the singular.

Przysługuje comes from przysługiwać, which means something like to be due, to be owed, to be granted by right, or to be something someone is entitled to.

So Dopłata przysługuje is not just an extra payment exists. It means the extra payment is due / is payable / is granted as a right.

This verb is especially common in:

• legal language
• employment language
• administrative decisions
• official regulations

For example:

• Przysługuje mu urlop. = He is entitled to leave.
• Przysługuje odszkodowanie. = Compensation is due.

Polish often leaves that unstated if it is clear from context.

In a fuller sentence, you might see:

• Dopłata przysługuje pracownikowi. = The employee is entitled to the additional payment.
• Dopłata przysługuje klientowi. = The customer is entitled to the additional payment.

In your sentence, the focus is on the rule itself, not on the person. So it sounds like an official statement: The additional payment is due, provided that...

Here o ile means provided that, as long as, or if.

So:

• Dopłata przysługuje, o ile potrącenie było błędem. means
• The additional payment is due, provided that the deduction was a mistake.

Important: o ile can also mean by how much / to what extent in other contexts.

For example:

• O ile droższe? = How much more expensive?

But in your sentence, it is clearly the conditional meaning: provided that.

Yes, in many contexts you could.

For example:

• Dopłata przysługuje, jeśli potrącenie było błędem.
• Dopłata przysługuje, jeżeli potrącenie było błędem.

All of these are understandable.

The difference is mostly in tone:

• jeśli / jeżeli = ordinary if
• o ile = often a bit more formal, legal, or rule-based; closer to provided that

Because the whole sentence sounds official, o ile fits very naturally.

Potrącenie usually means a deduction, especially from money such as:

• salary
• payment
• reimbursement
• invoice total

So in this sentence it most likely means a deduction that was made.

Be careful: the verb potrącić can have other meanings in other contexts, including to knock someone down / hit with a vehicle, but that is clearly not the meaning here.

In this sentence, potrącenie is a neuter noun.

Because potrącenie is a neuter noun.

Past tense forms of być agree with the gender of the subject:

• masculine: był
• feminine: była
• neuter: było

So:

• potrącenie było is correct because potrącenie is neuter.

Because after być, Polish very often uses the instrumental case for a predicate noun, especially when saying that something was / is something.

So:

• to było błędem = that was a mistake not
• to było błąd

Here:

• błąd = nominative
• błędem = instrumental

This is a very common pattern:

• To jest problemem.
• To było pomyłką.
• To jest rozwiązaniem.

In modern Polish, with some nouns and in some styles, nominative can sometimes appear in similar structures, but było błędem is the standard and natural form here.

Yes. Błąd and pomyłka are close in meaning, but they are not always identical in tone.

• błąd = error / mistake
• pomyłka = mistake / mix-up, often sounding a bit more like an accidental slip

So:

• potrącenie było błędem = the deduction was an error
• potrącenie było pomyłką = the deduction was a mistake / mix-up

In formal or administrative language, błędem often sounds a little more precise or official.

Here is the case breakdown:

• Dopłata — nominative singular
  It is the grammatical subject of przysługuje.

• potrącenie — nominative singular
  It is the subject of było in the subordinate clause.

• błędem — instrumental singular
  It is the predicate noun after było.

So the structure is roughly:

• [Dopłata] przysługuje
• o ile [potrącenie] było [błędem]

No, not completely. Polish word order is fairly flexible, though some orders sound more natural than others depending on emphasis.

The given version:

• Dopłata przysługuje, o ile potrącenie było błędem.

is natural and neutral in an official style.

You could also say:

• O ile potrącenie było błędem, dopłata przysługuje.

That puts more focus on the condition first.

Even so, in administrative language, the original order often sounds better because it states the rule first and then adds the condition.

Yes, definitely.

Several things make it sound formal or official:

• dopłata
• przysługuje
• o ile
• the abstract noun potrącenie
• the overall rule-like structure

A less formal everyday version might be something like:

• Dodatkowa kwota należy się, jeśli to potrącenie było pomyłką.

But the original sentence is exactly the kind of wording you might expect in:

• HR documents
• payroll explanations
• legal notices
• official correspondence