Mam przy sobie dowód, ale zapomniałem kopii dokumentu.

Przy sobie is an idiomatic Polish expression meaning on me / with me / on my person.

So Mam przy sobie dowód means I have my ID on me.

A grammar note:

• przy takes the locative
• sobie is the locative form of the reflexive pronoun

You will hear this pattern a lot:

• Masz przy sobie telefon? = Do you have your phone on you?
• Nie miałem przy sobie gotówki. = I didn’t have cash on me.

In Polish, subject pronouns are often omitted because the verb ending already shows who the subject is.

• mam = I have
• zapomniałem = I forgot (masculine speaker)

So ja is unnecessary unless you want emphasis or contrast:

• Ja mam przy sobie dowód, ale on nie ma. = I have ID on me, but he doesn’t.

The version without ja is the normal neutral one.

Because mieć normally takes the accusative case.

So the object of mam is in the accusative:

• mam co? → dowód

The tricky part is that for many masculine inanimate nouns, the nominative and accusative singular look the same. So:

• nominative: dowód
• accusative: dowód
• genitive: dowodu

That is why you see mam dowód, but for example:

• nie mam dowodu = I don’t have the ID / proof

Here, dowód most naturally means ID card, especially as shorthand for dowód osobisty.

On its own, dowód can also mean proof / evidence, but in a sentence about having it przy sobie and forgetting a copy of a document, the everyday reading is ID.

So in real-life Polish:

• Masz dowód? often means Do you have your ID?

Because Polish past tense agrees with the speaker’s gender.

• zapomniałem = I forgot (said by a man)
• zapomniałam = I forgot (said by a woman)

So a female speaker would say:

Mam przy sobie dowód, ale zapomniałam kopii dokumentu.

This is very normal in Polish: past tense forms often reveal the speaker’s gender.

Because zapomnieć is perfective, and here the sentence refers to a single completed event: I forgot.

• zapomniałem = I forgot / I ended up forgetting
• zapominałem = I was forgetting / I used to forget / I kept forgetting

In this sentence, the speaker means one finished action in the past, so zapomniałem is the natural choice.

This is a very common learner question.

With zapomnieć, Polish often uses the genitive when the meaning is to forget to take/bring something or to leave something behind.

So:

• zapomniałem kopii dokumentu = I forgot the copy of the document / I failed to bring it

This genitive pattern is very common with concrete things:

• zapomniałem paszportu
• zapomniałem biletu
• zapomniałem telefonu

If you say:

• zapomniałem o kopii dokumentu

that means I forgot about the copy of the document, which focuses more on the mental idea than on leaving it behind physically.

Because kopia normally combines with the genitive:

• kopia czego? = copy of what?
• kopia dokumentu = copy of the document

So in kopii dokumentu:

• kopii is genitive because of zapomniałem
• dokumentu is genitive because it depends on kopia

In other words, dokumentu means of the document.

Not necessarily.

The sentence most naturally means:

• I have my ID on me, but I forgot a copy of the document.

So dowód is probably your ID card, while dokument is some other document.

If you wanted to say that you forgot a copy of the ID itself, Polish would more naturally say:

• Mam przy sobie dowód, ale zapomniałem kopii dowodu.
• or more explicitly: kopii dowodu osobistego

So yes, the two nouns can refer to different things.

Yes. Both are natural.

• mam przy sobie dowód = I have my ID on me / on my person
• mam ze sobą dowód = I have my ID with me

The difference is small:

• przy sobie often emphasizes physical possession on your person
• ze sobą is a bit broader: with me

In this sentence, both work well.

Because Polish does not have articles like English a/an and the.

So:

• dowód can mean an ID, the ID, or just ID, depending on context
• kopii dokumentu can mean a copy of the document or the copy of the document

Polish relies on context, word order, and sometimes extra words like ten, jakiś, mój, etc. if the speaker wants to be more specific.

Yes. Polish word order is fairly flexible.

The original sentence is a neutral, natural version:

• Mam przy sobie dowód, ale zapomniałem kopii dokumentu.

But you could change the order for emphasis, for example:

• Dowód mam przy sobie, ale kopii dokumentu zapomniałem.

That puts stronger contrast on dowód versus kopii dokumentu.

So the original order is the safest neutral choice, but other orders are possible if you want a different emphasis.