Compare a restituição com o imposto devido.

Yes. Compare is the imperative form, so it means Compare... as a command or instruction.

In Brazilian Portuguese, this form is commonly used for:

• instructions
• forms
• manuals
• exercises
• official guidance

Here, Compare is most naturally understood as a command addressed to você (or sometimes a formal reader in general).

Portuguese often leaves out the subject when it is understood from the verb form or from context.

So instead of saying:

• Você compare a restituição com o imposto devido.

Portuguese normally just says:

• Compare a restituição com o imposto devido.

This sounds more natural in instructions and commands.

These are the definite articles:

• a = the for a feminine singular noun
• o = the for a masculine singular noun

So:

• a restituição = the refund / the reimbursement
• o imposto = the tax

Portuguese uses definite articles more often than English does, so keeping them in Portuguese is very normal.

Because it appears with a:

• a restituição

That tells you the noun is feminine.

Also, many nouns ending in -ção are feminine in Portuguese:

• a nação
• a informação
• a situação
• a restituição

This is a very useful pattern to remember.

In this context, restituição usually means a tax refund.

More generally, restituição can mean:

• restitution
• reimbursement
• refund

But with imposto in the same sentence, a learner should usually think of tax refund.

Yes. The most common pattern is:

• comparar X com Y = to compare X with Y

So:

• Compare a restituição com o imposto devido.

Portuguese can also use comparar X a Y, which is also correct, but com is very common and usually the easiest choice for learners.

So for everyday use, comparar ... com ... is a safe pattern to learn.

Here, devido means something like:

• owed
• due
• payable

So imposto devido means tax owed or tax due.

It is describing the noun imposto.

In Portuguese, adjectives often come after the noun.

So:

• imposto devido = literally tax due / owed tax

This post-noun position is very normal in Portuguese.

In English, adjectives usually come before the noun, but Portuguese often works differently:

• casa grande
• valor total
• imposto devido

Here it is functioning as an adjective.

It describes imposto:

• o imposto devido = the tax owed / due

It is related to the verb dever (to owe), but in this sentence it behaves like an adjective.

Yes, and it would be similar in meaning.

• o imposto devido = the tax owed / due
• o imposto a pagar = the tax to be paid / the tax payable

Both are possible, but imposto devido sounds especially common in formal, legal, tax, and administrative language.

A helpful approximation is:

• res-ti-tu-i-SÃO

Notes:

• The stress is on the last syllable: -ção
• -ção is a very common ending in Portuguese
• In Brazilian Portuguese, ção sounds roughly like sown with a nasal ending, though not exactly like English

So the key thing to remember is the stressed ending -ÇÃO.

It sounds like a sentence you might see in:

• tax instructions
• a government website
• accounting guidance
• a financial form
• a textbook exercise

The tone is neutral, direct, and somewhat formal. It is not especially conversational, but it is completely natural in written instructions.