Nakon selidbe prijavite promjenu adrese u policijskoj upravi.

Because the preposition nakon (after) requires the genitive case.

• selidba = moving, relocation
• genitive singular = selidbe

So:

• nakon selidbe = after the move / after moving

This is a very common pattern in Croatian:

• nakon ručka = after lunch
• nakon škole = after school
• nakon sastanka = after the meeting

Selidba means a move, moving house, or relocation. In this sentence it refers to the event of changing where you live.

It is a noun, not a verb. So Croatian is literally saying something like:

• After the move...

rather than:

• After you move...

Even though in English both are natural, Croatian often uses a noun phrase like this.

Prijavite is a finite verb form: specifically the imperative (command form), used here politely or formally.

• prijaviti = to report / to register
• prijavite = report / register

So the sentence is giving an instruction:

• Prijavite... = Report / Register...

This kind of wording is very common in official notices, instructions, and bureaucratic language.

Formally, prijavite can be:

• 2nd person plural imperative = you all report
• or formal singular imperative = you report when addressing one person politely

In public notices and official instructions, Croatian often uses this form to address the reader politely and generally, much like English instructions such as Please report... or Report...

So here it is not really about plural people specifically; it is the standard formal instruction form.

Here prijaviti means to report, to declare, or to register officially.

In administrative contexts, it often means notifying an authority of something. So:

• prijavite promjenu adrese = report/register the change of address

This verb is very common in official Croatian:

• prijaviti boravište = register temporary residence
• prijaviti prebivalište = register permanent residence
• prijaviti krađu = report a theft

Because promjenu adrese is the object of the verb prijavite, so promjena goes into the accusative case.

• nominative: promjena = change
• accusative: promjenu

The second noun, adrese, stays in the genitive because Croatian commonly expresses change of something with this pattern:

• promjena + genitive

So:

• promjena adrese = change of address
• prijavite promjenu adrese = report the change of address

Because it depends on promjena.

Croatian often links two nouns by putting the second one in the genitive, especially when English would use of:

• promjena adrese = change of address
• broj telefona = number of telephone / phone number
• ime grada = name of the city

So adrese is genitive singular of adresa.

Because the preposition u can take different cases depending on meaning.

Here it means in / at a place, so it uses the locative case:

• policijska uprava = police administration / police department
• locative singular = policijskoj upravi

So:

• u policijskoj upravi = at the police administration office / at the police department

Compare:

• u školi = in school
• u gradu = in the city
• u policijskoj upravi = at/in the police administration office

Literally, policijska uprava means police administration. In practice, it refers to the relevant police authority or office where administrative matters are handled.

Depending on context, English translations might include:

• police department
• police administration office
• police headquarters (sometimes, depending on local structure)

For a learner, the important thing is that this is the office/authority where you officially register the address change.

Yes, very formal and administrative.

Several things make it sound formal:

• the imperative prijavite
• the official verb prijaviti
• the bureaucratic phrase promjenu adrese
• the institutional location u policijskoj upravi

This is the kind of sentence you would see on:

• government websites
• official instructions
• forms
• public information notices

In casual speech, a person might say something less formal, but official Croatian often sounds like this.

Yes, poslije selidbe is possible and also means after the move.

However, nakon often sounds a bit more neutral or formal, which suits official instructions well.

So:

• nakon selidbe = a little more official/formal
• poslije selidbe = also correct, often more everyday

In bureaucratic language, nakon is very common.

The basic order is:

• Nakon selidbe = time expression
• prijavite = verb
• promjenu adrese = object
• u policijskoj upravi = place

So the sentence is structured like:

After moving, report the change of address at the police department.

Croatian word order is fairly flexible, so other orders are possible, especially for emphasis. But this order is natural and clear in official instructions.

For example, Croatian could also say:

• Promjenu adrese prijavite u policijskoj upravi nakon selidbe.

That would still be understandable, but the original version sounds more standard for an instruction.

Prijaviti is perfective.

That fits well here because the instruction is about completing a single official action: you are supposed to report/register the change.

Its imperfective partner is usually prijavljivati, which would suggest repeated or ongoing action.

So:

• prijaviti = report/register once, complete the action
• prijavljivati = be reporting, report repeatedly, do it as an ongoing process

In instructions for one completed administrative step, the perfective verb is the natural choice.