Kaucja nie jest mała, ale za media płacimy mniej niż w naszym starym mieszkaniu.

Kaucja is a security deposit, especially in renting. It is the money you pay up front and may get back later if there is no damage or unpaid rent.

It is a very common word in housing contexts in Polish.

Because kaucja is a feminine noun, and adjectives in Polish must agree with the noun in gender, number, and case.

So:

• mała kaucja = a small deposit
• kaucja nie jest mała = the deposit is not small

If the noun were masculine, you would use mały. If it were neuter, you would use małe.

Both are possible, but they are not exactly the same in tone.

• jest duża = it is big / large
• nie jest mała = it is not small

The version with nie jest mała is a bit softer and more indirect. It suggests the deposit is fairly high, without stating it as strongly as jest duża. English does this too with expressions like it’s not small.

In this sentence, jest is needed because nie jest mała is a normal full clause with the verb być = to be.

Polish sometimes omits to be in very informal speech, headlines, or certain special structures, but in standard full sentences like this one, you normally keep it:

• Kaucja jest mała = The deposit is small
• Kaucja nie jest mała = The deposit is not small

So here, jest is the standard and expected form.

Za media means for utilities in this context.

The preposition za is often used with płacić when talking about paying for something:

• płacić za prąd = to pay for electricity
• płacić za internet = to pay for internet
• płacić za media = to pay for utilities

Grammatically, za takes the accusative case here. The word media has the same form in nominative and accusative, so you do not see a change.

Yes, media can mean media in the usual English sense, but in housing and rental contexts it often means utilities or utility charges.

So in a sentence about an apartment, media usually means things like:

• water
• gas
• electricity
• heating
• sometimes internet or garbage collection, depending on context

This is a very common rental-related use of the word in Polish.

Because Polish verbs already show the subject in their endings.

Płacimy means we pay. The ending -my tells you it is 1st person plural.

So Polish often leaves out the pronoun my because it is unnecessary:

• płacimy = we pay
• my płacimy = we pay, with extra emphasis on we

In this sentence, there is no need to say my, because płacimy already makes it clear.

Mniej means less, and niż means than.

Together they form a comparison:

• mniej niż = less than

So:

• płacimy mniej niż... = we pay less than...

This is the normal Polish way to make this kind of comparison.

A few similar patterns are:

• więcej niż = more than
• tak samo jak = the same as
• mniej niż wcześniej = less than before

Because w meaning in takes the locative case when it describes location.

The base noun is mieszkanie = apartment / flat. In the locative singular, it becomes mieszkaniu.

The words modifying it also change to match:

• nasze stare mieszkanie = our old apartment
• w naszym starym mieszkaniu = in our old apartment

So the endings are there because the whole phrase is in the locative singular:

• naszym
• starym
• mieszkaniu

Because Polish, like English, often leaves out repeated information when it is already obvious.

The full sense is:

• we pay less than we did in our old apartment

Polish does not need to repeat the whole phrase for utilities or the whole verb phrase again, because the meaning is clear from context.

So płacimy mniej niż w naszym starym mieszkaniu is a natural, compact way to say it.

Yes. Polish word order is fairly flexible, although some versions sound more natural than others.

The given sentence is very natural:

• Kaucja nie jest mała, ale za media płacimy mniej niż w naszym starym mieszkaniu.

This order works well because it first gives one negative point, then contrasts it with a positive one:

• the deposit is high,
• but the utilities are cheaper than before.

You could move some parts around for emphasis, but the original sentence is a very normal and idiomatic choice.