A declaração pré-preenchida inclui o dependente e a dedução.

A is the feminine singular definite article, meaning the.

It is used because declaração is a feminine singular noun. In Portuguese, articles usually agree with the gender and number of the noun:

• a declaração = the declaration / the return
• o formulário = the form

Portuguese uses definite articles more often than English, so a sentence like this sounds natural with A.

Literally, declaração means declaration or statement.

But in this context, especially with words like dependente and dedução, it most likely refers to a tax return or tax declaration.

So even though the literal word is declaration, the real-life meaning is often something like:

• tax return
• tax declaration

Context matters a lot with this word.

Pré-preenchida means pre-filled or already filled in beforehand.

It is made from:

• pré- = pre-
• preenchida = filled in

So declaração pré-preenchida is a pre-filled declaration/tax return.

This is a very common bureaucratic or administrative expression in Brazilian Portuguese.

It has a hyphen because pré- is a prefix that normally keeps the hyphen when it is stressed and written with an accent.

So:

• pré-natal
• pré-história
• pré-preenchida

This is a spelling rule, not something optional.

Because adjectives in Portuguese usually agree with the noun they describe in gender and number.

Here, the noun is:

• declaração = feminine singular

So the adjective must also be feminine singular:

• pré-preenchida

Compare:

• o formulário pré-preenchido = the pre-filled form
• a declaração pré-preenchida = the pre-filled declaration
• as declarações pré-preenchidas = the pre-filled declarations

Because in Portuguese, adjectives usually come after the noun.

So the normal order is:

• declaração pré-preenchida

rather than putting the adjective first, as English often does.

This noun + adjective order is very common in Portuguese:

• carro novo = new car
• casa grande = big house
• declaração pré-preenchida = pre-filled declaration

Inclui is the third person singular present tense form of incluir = to include.

The subject is A declaração pré-preenchida, which is singular, so the verb must also be singular:

• A declaração ... inclui = The declaration includes

A few present-tense forms of incluir are:

• eu incluo = I include
• você/ele/ela inclui = you/he/she include(s)
• nós incluímos = we include
• eles/elas incluem = they include

So inclui is exactly the form you would expect here.

Because incluir is a direct transitive verb in Portuguese. That means it takes a direct object without a preposition.

So you say:

• inclui o dependente
• inclui a dedução

not:

• inclui ao dependente
• inclui da dedução

This works like English include, which also usually takes a direct object.

Yes. Dependente is one of those nouns/adjectives whose ending does not change between masculine and feminine. The article shows the gender:

• o dependente = the male dependent, or masculine/generic dependent
• a dependente = the female dependent

So the word itself stays the same, but the article changes.

In a tax context, dependente means a person claimed as a dependent.

Because dedução is a feminine noun, so it takes a:

• a dedução = the deduction

Many Portuguese nouns ending in -ção are feminine:

• a declaração
• a dedução
• a informação
• a situação

So once you learn that pattern, this becomes easier to predict.

Sometimes yes, but context is important.

In this sentence, dedução almost certainly means a tax deduction.

English deduction can also mean logical reasoning, as in I made a deduction. Portuguese can use dedução that way too, but here the tax context makes the meaning clear.

So in this sentence, think:

• dedução = tax deduction

A useful approximation is:

• declaração ≈ deh-kla-rah-SOWN
• dedução ≈ deh-doo-SOWN

A few pronunciation notes:

• -ção is very common in Portuguese and is roughly like sown with a nasal sound.
• -ão is a nasal ending that English does not have exactly.
• The stress in both words falls on the last syllable:
  • decla-ra-ÇÃO
  • dedu-ÇÃO

You do not pronounce the final m or n sound like in English; instead, the vowel becomes nasal.

Yes. It is especially common in official, financial, and tax-related language.

In Brazil, declaração pré-preenchida is a normal phrase for a form or tax return that already comes with information filled in automatically.

So even though it may feel long or formal to an English speaker, it is completely natural in bureaucratic Brazilian Portuguese.