Untungnya, kartu identitas saya tidak terbawa ke kantor seperti kemarin.

Untungnya means fortunately or luckily.

The base word is untung, which means luck, good fortune, or sometimes profit depending on context.

In untungnya, the -nya does not mean his/her/its here. Instead, it helps turn the idea into something like:

• fortunately
• the fortunate thing is...
• luckily

So Untungnya, ... is a very natural sentence opener when you want to say that something turned out well.

Examples:

• Untungnya, saya ingat. = Fortunately, I remembered.
• Untungnya, hujan sudah berhenti. = Luckily, the rain has stopped.

In Indonesian, possession usually works like this:

noun + possessor

So:

• kartu identitas saya = my ID card
• literally: identity card my

This is normal Indonesian word order.

More examples:

• rumah saya = my house
• nama Anda = your name
• teman mereka = their friend

So kartu identitas saya is exactly the expected structure.

Kartu identitas literally means identity card or ID card.

It is a fairly general term. Depending on context, it could refer to:

• a national ID card
• a work ID card
• some other identification card

In everyday Indonesian, if someone specifically means the Indonesian national ID card, they often say KTP. But kartu identitas is still perfectly understandable and more general.

This is one of the most important parts of the sentence.

• membawa = to bring / to carry
• terbawa = to get carried / to end up being brought along, often unintentionally

So:

• Saya tidak membawa kartu identitas saya ke kantor.
  = I did not bring my ID card to the office.
  This focuses on my action.

• Kartu identitas saya tidak terbawa ke kantor.
  = My ID card did not get brought to the office / did not end up coming along to the office.
  This focuses on what happened to the card.

The version with terbawa sounds more like the speaker is talking about whether the card happened to come along, not about a deliberate action.

The prefix ter- can have several uses in Indonesian, but in sentences like this it often gives one of these ideas:

• something happened accidentally
• something happened without intention
• something ended up in a certain state
• a kind of passive-like meaning

So terbawa often suggests:

• got carried along
• ended up being brought
• was accidentally brought

In this sentence, tidak terbawa means the card did not end up coming along to the office.

A few similar examples:

• tertinggal = got left behind
• terbuka = opened / got opened / is open
• terbawa arus = got carried away by the current

So ter- often shifts the focus away from a deliberate actor and toward the resulting situation.

Because tidak is the normal negator for verbs and adjectives in Indonesian.

Here, terbawa functions as the verbal part of the sentence, so:

• tidak terbawa = did not get brought along

Compare:

• saya tidak tahu = I do not know
• dia tidak datang = he/she did not come
• pintunya tidak terbuka = the door is not open / did not open

So the placement is very standard: tidak + verb/adjective.

Because ke shows movement toward a destination, while di shows location.

• ke kantor = to the office
• di kantor = at the office / in the office

Since the sentence is talking about whether the ID card was brought to the office, ke is the correct preposition.

Compare:

• Saya pergi ke kantor. = I go to the office.
• Saya ada di kantor. = I am at the office.

Here seperti kemarin means something like:

• as happened yesterday
• like yesterday
• the way it was yesterday

It refers to the whole situation, not just to kantor.

So the sense is:

• Fortunately, my ID card did not get brought to the office, unlike yesterday / the way it did yesterday.

In other words, yesterday the card was brought to the office, and today that did not happen.

This kind of shortened comparison is very common in Indonesian. The full idea is understood from context without repeating everything.

The structure is:

• Untungnya = fortunately
• kartu identitas saya = my ID card
• tidak terbawa = did not get brought along / did not end up being brought
• ke kantor = to the office
• seperti kemarin = like yesterday / as happened yesterday

So the sentence is built as:

Fortunately + subject + negated predicate + destination + comparison

The grammatical subject is kartu identitas saya.

That may feel a little unusual to an English speaker, because English would often prefer:

• Fortunately, I didn't bring my ID card to the office like yesterday.

But Indonesian often allows the thing affected by the action to be the focus:

• My ID card didn’t end up coming along to the office.

Yes, that is a very natural English translation, but it is not a word-for-word match.

Why? Because the Indonesian sentence with tidak terbawa is slightly less direct than saya tidak membawa.

Compare the nuance:

• Saya tidak membawa kartu identitas saya ke kantor.
  = I did not bring my ID card to the office.
  Stronger focus on my action.

• Kartu identitas saya tidak terbawa ke kantor.
  = My ID card did not get brought to the office.
  Stronger focus on what happened to the card, often with a slightly accidental or unplanned feeling.

So your English translation is fine, but the Indonesian sentence carries a nuance of it didn’t end up coming along, rather than simply I chose not to bring it.