A taxa de condomínio e a contribuição extraordinária estão altas.

Because Portuguese normally repeats the definite article before each noun in a list when each noun has its own modifier or is being clearly identified.

So:

• A taxa de condomínio = the condo fee
• a contribuição extraordinária = the special/extra contribution

This is more natural than trying to use just one article for both nouns.

English often says the condo fee and special contribution, but Portuguese usually keeps the article with each noun:

• A taxa ... e a contribuição ...

De condomínio means of the condominium / condo-related.

In Brazilian Portuguese, taxa de condomínio is the regular fee residents pay for building maintenance, shared services, security, etc.

Structure:

• taxa = fee/rate
• de = of / for
• condomínio = condominium / apartment building association / condo complex

So taxa de condomínio is a fixed expression meaning something like condo fee or building maintenance fee.

It means an extraordinary contribution, usually an extra payment charged in addition to the regular condo fee.

In real-life Brazilian usage, this often refers to a temporary extra charge for things like:

• repairs
• renovations
• emergency expenses
• major building work

So:

• contribuição = contribution/payment
• extraordinária = extraordinary, special, outside the usual routine

Because the subject is plural.

The sentence has two things joined by e (and):

• A taxa de condomínio
• a contribuição extraordinária

Together, they form a plural subject, so the verb must also be plural:

• singular: está
• plural: estão

Compare:

• A taxa de condomínio está alta. = The condo fee is high.
• A taxa de condomínio e a contribuição extraordinária estão altas. = The condo fee and the extra contribution are high.

Because altas agrees with the two nouns it describes.

Both nouns are:

• feminine
• taken together, plural

So the adjective must also be:

• feminine plural → altas

Breakdown:

• alto = masculine singular
• alta = feminine singular
• altos = masculine plural
• altas = feminine plural

Since taxa and contribuição are both feminine nouns, Portuguese uses altas.

Because this sentence uses estar + adjective, which is a very common way to describe a condition or state.

Structure:

• [subject] + estão + altas

So:

• A taxa de condomínio e a contribuição extraordinária estão altas.

This works like:

• The fees are high.

If you put the adjective before the nouns, you would be building a different kind of structure, not this exact one. Here, altas is a predicate adjective linked by estar.

In Portuguese, estar is commonly used for conditions or states that can vary, including prices, fees, costs, temperatures, and similar things.

So estão altas means they are high right now / currently / in this situation.

Examples:

• Os preços estão altos. = Prices are high.
• A conta de luz está alta. = The electricity bill is high.

Using ser here would sound unnatural in normal Brazilian Portuguese.

In normal Brazilian Portuguese, estão altas is the natural choice for costs, fees, prices, and bills.

São altas is usually not the best option here. Portuguese tends to treat this as a current condition rather than an essential characteristic.

So for money-related situations, prefer:

• está alto / está alta
• estão altos / estão altas

Examples:

• Os aluguéis estão altos.
• As taxas estão altas.

Because each noun has its own gender, and one noun does not change the gender of another.

• taxa is feminine → a taxa
• condomínio is masculine → o condomínio
• contribuição is feminine → a contribuição

In taxa de condomínio, the main noun is taxa, so the whole expression is feminine:

• a taxa de condomínio

The phrase de condomínio only adds information; it does not control the article or adjective agreement.

Yes, alto/alta can mean tall or high, depending on context.

With costs, prices, fees, bills, and amounts, it usually means high:

• preço alto = high price
• taxa alta = high fee/rate
• conta alta = high bill

So in this sentence, altas means high, not tall.

Sometimes yes, but the meaning shifts slightly.

• altas focuses on the amount being high
• caras focuses more on something being expensive

For fees, bills, and rates, altas is very natural and common. You may also hear:

• As taxas estão caras in some contexts

But taxas estão altas sounds more standard for talking about rates/fees themselves.

The full subject is:

A taxa de condomínio e a contribuição extraordinária

The simple nouns at the core are:

• taxa
• contribuição

Everything else modifies them:

• de condomínio modifies taxa
• extraordinária modifies contribuição

Then the predicate is:

• estão altas

So the sentence structure is:

• Subject: A taxa de condomínio e a contribuição extraordinária
• Verb: estão
• Adjective/complement: altas

Then you would use singular agreement.

Examples:

• A taxa de condomínio está alta.
• A contribuição extraordinária está alta.

If both are high, use plural:

• A taxa de condomínio e a contribuição extraordinária estão altas.

So the change is:

• singular subject → está alta
• plural subject → estão altas