Manjak je zbog troška.

Because zbog requires the genitive case.

The basic dictionary form is trošak. After zbog (because of / due to), that noun changes to genitive singular:

• trošak → nominative singular
• troška → genitive singular

So:

• zbog troška = because of the expense / due to the cost

This is one of the most important things to memorize with Serbian prepositions: many of them require a specific case.

Manjak is in the nominative singular.

In this sentence, it is the main noun of the sentence, so it stays in its basic form:

• manjak = nominative singular

Structurally, the sentence is:

• Manjak = the shortage/deficit/lack
• je = is
• zbog troška = because of the expense

So manjak is the thing being talked about, while zbog troška explains the cause.

Zbog means because of, due to, or on account of.

It is used before a noun phrase, not a full clause. It always takes the genitive.

Examples:

• zbog kiše = because of the rain
• zbog problema = because of the problem
• zbog troška = because of the expense

If you want to say because before a whole sentence, Serbian often uses something else, such as zato što.

So a useful contrast is:

• zbog + noun
• zato što + clause

Yes, it could be plural, depending on the meaning.

• zbog troška = because of one specific expense / one cost item
• zbog troškova = because of costs / expenses in general

So if the context is about one particular charge or expense, singular makes sense. If the idea is broader, Serbian would often use the plural:

• Manjak je zbog troškova.

That can sound more natural in contexts where English would say because of costs.

No, Serbian word order is fairly flexible.

Manjak je zbog troška is a normal sentence, but the order can change for emphasis:

• Zbog troška je manjak.
  This puts more focus on the cause.

Still, not every possible order sounds equally natural in every context. The original order is straightforward and easy to understand.

In Serbian, word order often helps show focus or emphasis, not just grammar.

Yes, in a normal full sentence, je is normally kept.

Je is the 3rd person singular present form of biti (to be). In this sentence, it works like is.

So:

• Manjak je zbog troška. = normal full sentence

If you remove je, the result may sound like a note, headline, or very elliptical style rather than standard everyday sentence grammar.

Yes, both are masculine singular nouns.

They both end in a consonant in the nominative singular, which is a common sign of masculine nouns in Serbian:

• manjak
• trošak

A few useful forms:

• manjak → genitive manjka
• trošak → genitive troška

So the pattern in the sentence is very typical Serbian grammar:

• nominative for the main noun
• genitive after zbog

Because Serbian does not have articles like English.

So manjak can mean:

• a shortage
• the shortage

And trošak / troška can mean:

• a cost / expense
• the cost / expense

The exact meaning depends on context, not on an article.

This is very normal in Serbian, so learners need to get used to understanding definiteness from the situation rather than from words like the and a.

It is understandable and grammatically fine, but whether it sounds perfectly natural depends on the context.

A native speaker might sometimes prefer a slightly fuller sentence, for example if they want to make the causal relationship more explicit. But Manjak je zbog troška is not wrong.

One thing that affects naturalness is whether trošak is meant as:

• one particular expense, or
• expenses/costs in general

If the second meaning is intended, zbog troškova may sound more natural.

So the sentence is good for learning these points:

• zbog + genitive
• nominative subject
• normal use of je
• flexible word order