La quota condominiale dipende dai millesimi.

Because quota is a feminine singular noun in Italian, so it takes the feminine singular article la.

Agreement works like this:

• la quota
• una quota
• quote in the plural

So the article must match the gender and number of the noun.

Condominiale is an adjective meaning something like related to the condominium / apartment building association.

So:

• quota = share, fee, amount
• condominiale = condominium-related

Together, quota condominiale means the condo fee/share/charge.

In Italian, adjectives often come after the noun, so quota condominiale is the normal order.

Because in Italian, adjectives commonly follow the noun they describe.

So:

• quota condominiale = condominium fee
• spesa mensile = monthly expense
• assemblea annuale = annual meeting

English often puts adjectives before the noun, but Italian very often puts them after. That is one of the most common word-order differences for English speakers.

Because the subject is la quota condominiale, which is singular.

The verb dipendere must agree with its subject:

• la quota dipende
• le quote dipendono

Even though millesimi is plural, it is not the subject. It is the thing the fee depends on.

Because the verb dipendere normally takes the preposition da when it means to depend on.

So:

• dipendere da qualcosa = to depend on something
• dipende dal tempo = it depends on the weather
• dipende da te = it depends on you
• dipende dai millesimi = it depends on the thousandths/shares

This is something you mostly just have to learn with the verb: dipendere da.

Because in Italian, da + i contracts to dai.

Here is the pattern:

• da + il = dal
• da + lo = dallo
• da + la = dalla
• da + i = dai
• da + gli = dagli
• da + le = dalle

Since millesimi is masculine plural and takes i, you get:

• da + i millesimi = dai millesimi

In condominium language, i millesimi are the ownership shares expressed in thousandths of the whole building.

They are used in Italy to calculate things such as:

• condominium fees
• voting weight in building meetings
• each owner’s share of common expenses

So this word is very specific to property/condominium contexts. It does not just mean any random thousandths here; it refers to the official allocation of shares in the building.

Because in this context it refers to the shares/thousandths assigned to a property, and that idea is normally expressed in the plural.

Singular:

• il millesimo

Plural:

• i millesimi

In real estate/condominium language, people usually talk about i millesimi because a property has a certain number of thousandths, not just one.

Yes, you could, if you want to make it explicit whose shares you mean.

• dipende dai millesimi = depends on the thousandths/shares
• dipende dai suoi millesimi = depends on its/your/his/her shares, depending on context

Italian often leaves out possessives when the meaning is already clear, especially in general statements. So dai millesimi sounds natural and normal here.

It can easily be understood as a general rule.

The present tense dipende often expresses:

• a general fact
• a rule
• something that is regularly true

So La quota condominiale dipende dai millesimi sounds like a general statement such as The condo fee depends on the ownership shares.

If the context were specific, it could also refer to one particular fee, but without more context, it sounds like a general truth.

The normal, neutral order is:

La quota condominiale dipende dai millesimi.

Italian does allow some flexibility, but changes in order usually add emphasis. For example:

• Dai millesimi dipende la quota condominiale sounds more marked and emphasizes dai millesimi
• La quota dipende dai millesimi condominiali would change the structure and could sound less natural in this exact meaning

For a learner, the original sentence is the best version to use.

Very often, yes, they can express a similar idea.

For example:

• quota condominiale
• quota del condominio

But they are not always identical in style or usage.

Condominiale is an adjective and is very common in fixed expressions such as:

• spese condominiali
• assemblea condominiale
• regolamento condominiale

Using the adjective often sounds more compact and idiomatic than a longer di + noun phrase.