Ne idem na posao zato što imam temperaturu.

Ne idem is the correct way to say I am not going / I don’t go in the present tense.

• idem = I go / I am going
• ne idem = I don’t go / I’m not going

Croatian usually makes present-tense verbs negative by putting ne before the verb:

• radim → ne radim
• znam → ne znam
• idem → ne idem

Forms like nisam idem are not possible, because nisam is used with the past participle, not with a present-tense verb.

Croatian often leaves out subject pronouns because the verb ending already tells you who the subject is.

• idem already means I go / I’m going
• the ending -m shows first person singular

So Ja ne idem na posao is possible, but ja is usually only added for emphasis, contrast, or clarity:

• Ja ne idem na posao, ali on ide.
  I’m not going to work, but he is.

Idem is the 1st person singular present tense of ići (to go).

In this sentence, it most naturally means:

• I’m not going to work
• or I’m not going in to work

Croatian present tense can cover both:

• a general present meaning: I don’t go
• a current/near-future meaning: I’m not going

So in context, this sentence usually means I’m not going to work because I have a fever.

Because Croatian idiomatically says ići na posao for to go to work.

This is just the normal expression:

• Idem na posao. = I’m going to work.

Even though na often means on/to, prepositions do not translate word-for-word between languages. Here, na posao is simply the standard phrase.

u posao usually does not mean to work in this context. It can sound like into the work, into business, or something more abstract.

So for everyday meaning to go to work, use:

• ići na posao
• doći na posao = come to work
• kasniti na posao = be late for work

In na posao, the noun posao is in the accusative singular because na with movement usually takes the accusative.

• ići na + accusative = go to

The noun posao is masculine inanimate, and for many masculine inanimate nouns, the accusative singular looks the same as the nominative singular.

So:

• nominative: posao
• accusative: posao

That is why it looks unchanged.

Yes. Zato što means because.

It is a very common and natural way to introduce a reason:

• Ne idem na posao zato što imam temperaturu.
  I’m not going to work because I have a fever.

Another very common option is jer:

• Ne idem na posao jer imam temperaturu.

Both are natural. Very roughly:

• zato što can sound a little fuller or more explicit
• jer is shorter and very common in everyday speech

Yes, absolutely.

You can say:

• Ne idem na posao zato što imam temperaturu.
• Ne idem na posao jer imam temperaturu.

Both mean the same thing: I’m not going to work because I have a fever.

A learner will hear jer very often in everyday Croatian because it is short and convenient.

In Croatian, imam temperaturu is a normal way to say I have a fever.

Literally, temperatura is temperature, but in everyday use it often means an elevated body temperature, so the whole phrase means to have a fever.

So:

• Imam temperaturu. = I have a fever.

This is very natural Croatian.

Because temperaturu is the accusative singular form of temperatura.

The verb imati (to have) takes a direct object, and that object goes in the accusative:

• imam knjigu = I have a book
• imam sestru = I have a sister
• imam temperaturu = I have a fever

So:

• nominative: temperatura
• accusative: temperaturu

Because Croatian present tense often covers situations that English expresses with either:

• simple present: I don’t go
• or present continuous / near future: I’m not going

In context, Ne idem na posao usually means something like:

• I’m not going to work today
• I’m not going in to work
• I’m not going right now

So Croatian does not need a separate continuous form like English does.

By itself, it could technically depend on context, but in real life it most naturally means a temporary current situation:

• I’m not going to work because I have a fever.

The reason clause because I have a fever strongly suggests a temporary situation, not a permanent habit.

If someone meant a general habitual statement, the context would usually make that clear.

Yes. Croatian word order is fairly flexible.

The original sentence is natural and neutral:

• Ne idem na posao zato što imam temperaturu.

You can also say:

• Zato što imam temperaturu, ne idem na posao.

This puts the reason first, a bit like:

• Because I have a fever, I’m not going to work.

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

Usually, this sentence is written without a comma before zato što:

• Ne idem na posao zato što imam temperaturu.

If the reason clause comes first, then you normally put a comma after it:

• Zato što imam temperaturu, ne idem na posao.

So the version you were given is punctuated in a normal way.

No, not exactly.

• Ne idem na posao = I’m not going to work
• Ne radim = I’m not working

These can overlap, but they are not always the same.

For example:

• If you are sick and staying home, you can say Ne idem na posao.
• Ne radim can also mean I’m unemployed or I’m not working right now.

So in this sentence, ne idem na posao is more precise because it focuses on not going in to work.

Yes, ići is somewhat irregular, so learners often notice this form.

Present tense:

• idem = I go
• ideš = you go
• ide = he/she/it goes
• idemo = we go
• idete = you go
• idu = they go

So idem is just the normal present form of ići, even if it does not look exactly like the infinitive.

Yes, very natural.

A Croatian speaker could easily say:

• Ne idem na posao zato što imam temperaturu.
• Ne idem na posao jer imam temperaturu.

Both sound normal and everyday. The sentence is a very good example of how Croatian expresses a reason in an ordinary real-life situation.