Do rachunku płatniczego mam kartę debetową.

In this sentence, do means something like for, for use with, or attached to.

So:

• karta debetowa do rachunku płatniczego = a debit card for / linked to a payment account

This is a very common use of do in Polish: it can show purpose, connection, or suitability, not just movement.

Compare:

• Idę do banku = I’m going to the bank
• Klucz do drzwi = a key for the door
• Karta do rachunku = a card for the account

So here, do expresses a relationship between the card and the account.

Because the preposition do requires the genitive case.

The basic form is:

• rachunek płatniczy = payment account

After do, both words change to genitive singular:

• rachunek → rachunku
• płatniczy → płatniczego

So:

• do rachunku płatniczego = for/to the payment account

This is something you’ll see often in Polish: the preposition determines the case.

Because kartę debetową is the accusative case, used here for the direct object of mam (I have).

Base form:

• karta debetowa = nominative

After mam, we need the thing being had, so we use accusative:

• mam kartę debetową = I have a debit card

For feminine nouns ending in -a, the accusative singular usually changes:

• karta → kartę

And the adjective changes too:

• debetowa → debetową

Because in Polish, adjectives must agree with the noun they describe in:

• gender
• number
• case

So:

• rachunek płatniczy → do rachunku płatniczego
• karta debetowa → kartę debetową

The adjective copies the grammatical form of the noun. This is a core feature of Polish grammar.

Yes, it is natural, but it has a particular emphasis.

Polish word order is more flexible than English. Starting with Do rachunku płatniczego puts the account first as the topic:

• Do rachunku płatniczego mam kartę debetową. = As for the payment account, I have a debit card for it.

A more neutral order would often be:

• Mam kartę debetową do rachunku płatniczego.

Both are correct. The difference is mostly about emphasis and information structure, not basic meaning.

Yes, absolutely. That is probably the more straightforward word order for many learners.

Compare:

• Mam kartę debetową do rachunku płatniczego.
  More neutral: I have a debit card for the payment account.

• Do rachunku płatniczego mam kartę debetową.
  More topical/emphatic: For the payment account, I have a debit card.

Polish often moves phrases around depending on what is already known and what is being emphasized.

Polish normally expresses possession with mieć (to have), just like English in many cases.

So:

• mam kartę = I have a card

Polish can sometimes express possession in other ways, especially with u mnie jest... or jestem w posiadaniu..., but those are different in tone or meaning.

In everyday speech, mam is the normal and simple way to say I have.

Rachunek płatniczy is a formal banking term meaning payment account. In many contexts, it may refer to what English speakers would loosely think of as a bank account, especially one used for everyday payments.

However:

• konto is more common in everyday speech
• rachunek płatniczy sounds more official, legal, or banking-related

So in casual speech, many people might say:

• Mam kartę debetową do konta.

That would sound more natural in ordinary conversation, while rachunek płatniczy sounds like wording from a bank document or website.

Yes. The standard term is:

• karta debetowa = debit card

And for comparison:

• karta kredytowa = credit card

So debetowa is the correct adjective formed from debet.

No. Rachunek has several meanings depending on context. It can mean:

• account (especially financial)
• bill
• check (restaurant check)
• calculation

That’s why context matters a lot.

For example:

• rachunek bankowy = bank account
• poproszę rachunek = the bill, please
• rachunek matematyczny = a calculation

In your sentence, because of płatniczy, it clearly means a financial account.

No. Polish has no articles, so there is no direct equivalent of English a/an/the.

That means:

• mam kartę debetową could mean I have a debit card or I have the debit card, depending on context.

The listener understands which meaning is intended from the situation, word order, and emphasis.

Sometimes literally, yes, but in this sentence that would sound unnatural in English.

Polish do often covers meanings that English expresses in different ways. Here, the best natural English translation is more like:

• for the account
• linked to the account
• for use with the account

So while do can literally correspond to to, that is not always the best translation.

It is grammatically correct, but it sounds somewhat formal because of rachunek płatniczy.

In real everyday conversation, many speakers would be more likely to say:

• Mam kartę debetową do konta.
• Do konta mam kartę debetową.

Those sound more natural in ordinary speech.

Your original sentence sounds like something from:

• a bank form
• a customer service message
• a financial explanation
• legal or official language

Yes, that is exactly what the structure suggests.

The phrase:

• karta debetowa do rachunku płatniczego

does not just list two separate things. It strongly implies a connection:

• the debit card is issued for
• associated with
• linked to that account.

So the sentence means more than I have a debit card and a payment account. It means the card is connected to that account.