O contribuinte pode deduzir a despesa médica.

In Portuguese, it is very common to use the definite article with nouns, especially in formal or legal-style sentences.

So o contribuinte means the taxpayer, but it can also refer to the taxpayer in general / any taxpayer depending on context.

This kind of wording is common in rules, instructions, and tax language:

• O contribuinte deve guardar os recibos.
• O empregador deve informar os salários.

In English, we often leave the article out in this kind of general statement, but Portuguese usually keeps it.

No. Contribuinte is a noun that can refer to either a man or a woman. The word itself does not change form.

What changes is the article:

• o contribuinte = the taxpayer (male, or generic)
• a contribuinte = the taxpayer (female)

In legal or administrative language, the masculine article is often used in a generic sense, but if the person is specifically female, a contribuinte is also correct.

Pode is the 3rd person singular of poder = can / may / be able to.

After a conjugated modal verb like poder, the next verb usually stays in the infinitive:

• pode deduzir = can deduct
• pode pagar = can pay
• pode declarar = can declare

So the structure is:

subject + pode + infinitive

Here:

• O contribuinte = subject
• pode = can/may
• deduzir = deduct

It can suggest either one, depending on context.

In a sentence like this, especially in tax or legal language, pode often means:

• is allowed to
• is permitted to
• may
• sometimes simply can

So O contribuinte pode deduzir a despesa médica usually means that the taxpayer is allowed by the rules to deduct that expense.

Not always, and this is a useful point for English speakers.

In English, deduce usually means infer / work out logically.

In Portuguese, deduzir can also mean infer, but in financial and tax contexts it commonly means deduct.

So in this sentence, deduzir means:

• to deduct
• not to figure out

This is a context-dependent word.

Yes, English often uses the plural medical expenses, and Portuguese can also say despesas médicas.

But the singular a despesa médica is also natural, especially in formal, legal, or tax language, where a singular noun can represent a category in a general sense:

• a despesa médica = medical expense as a category / this type of expense

So this sentence may be talking about:

• a medical expense in general, as a deductible category, or
• a specific medical expense, depending on context

Both singular and plural can appear in real Portuguese, but the singular sounds especially official here.

In Portuguese, adjectives usually come after the noun.

So:

• despesa médica = medical expense
• despesa hospitalar = hospital expense
• recibo médico = medical receipt

English usually puts adjectives before the noun, but Portuguese often puts them after.

That is why:

• medical expense becomes despesa médica not médica despesa

Usually, despesa médica is the normal and natural expression.

Despesa de médico would sound more like:

• expense involving a doctor
• a doctor’s expense
• or something more specific and less standard

In tax language, despesa médica is the expected term for medical expense.

A helpful approximation in Brazilian Portuguese is:

con-tree-boo-EEN-chee

The stress falls on uin:

• con-tri-bu-in-te

A few notes:

• tri sounds roughly like tree
• buin forms a glide, not a fully separate English-style syllable
• final te in Brazilian Portuguese often sounds like chee in many accents

So a rough learner-friendly pronunciation is: con-tree-boo-EEN-chee

A simple Brazilian Portuguese approximation:

• pode ≈ POH-jee or POH-dee depending on accent
• deduzir ≈ deh-doo-ZEER

Notes:

• In many Brazilian accents, unstressed de and di can sound like jee and chee, but this varies.
• The stress in deduzir is on the last syllable: de-du-zir

Yes, but the original order is the most neutral and standard:

O contribuinte pode deduzir a despesa médica.

Portuguese word order is fairly flexible, but changes can affect style or emphasis.

For example:

• A despesa médica o contribuinte pode deduzir.
  This puts emphasis on medical expense, and sounds more marked.
• Pode o contribuinte deduzir a despesa médica?
  This sounds formal or legalistic, and can feel like a question or a very formal statement depending on punctuation and context.

For normal use, the original sentence is the best model.

Because deduzir is a direct transitive verb in this meaning. It takes a direct object without a preposition.

So:

• deduzir algo = deduct something

Here:

• a despesa médica is the direct object

Compare:

• deduzir a despesa
• deduzir o valor
• deduzir os gastos

No preposition is needed.

Yes, absolutely.

O contribuinte pode deduzir despesas médicas means The taxpayer can deduct medical expenses, and it sounds very natural.

The difference is mostly one of framing:

• a despesa médica = medical expense as a category, or a specific expense depending on context
• despesas médicas = medical expenses in general, more explicitly plural

In real-world tax language, both can appear. The version you were given has a slightly more formal, category-based feel.