Eu vou pagar o DAS amanhã.

Yes. In Brazilian Portuguese, you can often drop the subject pronoun when the verb already makes the subject clear.

So both of these are possible:

• Eu vou pagar o DAS amanhã.
• Vou pagar o DAS amanhã.

Including eu can make the sentence a little more explicit, emphatic, or contrastive. For example, it may help if you want to stress I am the one who will pay it.

Vou pagar is a very common future construction in Portuguese:

• vou = I go / I am going
• pagar = to pay

Together, ir + infinitive means going to + verb in English.

So:

• vou pagar = I am going to pay

This is one of the most common ways to talk about the future in everyday Brazilian Portuguese.

Both are possible, but they sound different in style and usage.

• Vou pagar o DAS amanhã. = very natural in everyday speech
• Pagarei o DAS amanhã. = correct, but more formal, less common in conversation

In modern spoken Brazilian Portuguese, ir + infinitive is usually preferred for ordinary future meaning.

In Brazil, DAS usually refers to a specific payment document/tax slip, especially in business or tax contexts. Very often it means Documento de Arrecadação do Simples Nacional.

Since the meaning is already known to the learner, the important grammar point is that Portuguese treats it like a noun, so it can take an article:

• o DAS

This is similar to saying the DAS in English if the acronym refers to a specific known item.

Portuguese uses definite articles much more often than English does. Acronyms and named documents frequently appear with an article.

So o DAS means something like:

• the DAS
• the DAS payment slip/document

The article is masculine singular: o.

In practical usage, learners should just remember that Brazilians commonly say pagar o DAS, emitir o DAS, baixar o DAS, and so on.

It is treated as a masculine noun.

This often happens because the acronym refers to a masculine head word, such as documento, which is masculine. So the article follows that grammatical gender:

• o documento
• o DAS

With acronyms in Portuguese, gender often comes from the main noun behind the abbreviation.

In real life, many Brazilians pronounce DAS as a single syllable, like das, rather than spelling out each letter.

So in this context it is often said like:

• o DAS

rather than:

• o D-A-S

That said, pronunciation of acronyms can vary by person and context.

Amanhã means tomorrow and works here as a time adverb.

Putting time expressions at the end is very common and natural:

• Eu vou pagar o DAS amanhã.

But Portuguese word order is flexible, so these are also possible:

• Amanhã eu vou pagar o DAS.
• Eu amanhã vou pagar o DAS.
  This one is possible, but less neutral.

The version with amanhã at the end sounds very normal.

No. Amanhã is used directly, without a preposition.

Correct:

• Eu vou pagar o DAS amanhã.

Not natural:

• Eu vou pagar o DAS em amanhã.

This is similar to English tomorrow, which also does not need a preposition in this kind of sentence.

Because pagar is usually a direct transitive verb when it takes the thing being paid.

You pay something:

• pagar o DAS
• pagar a conta
• pagar o boleto

So there is no preposition before the object here.

But when you say who receives the payment, Portuguese may use a preposition:

• pagar a conta ao garçom
• pagar ao fornecedor

So in your sentence, o DAS is the direct object.

Yes, and that can be confusing for English speakers.

Portuguese often says simply:

• pagar a conta
• pagar o boleto
• pagar o DAS

Where English may say:

• pay the bill
• pay the slip
• pay the DAS or sometimes
• pay for something, depending on the context

So learners should focus on the Portuguese pattern, not try to match English prepositions too closely.

It is future in meaning, but it often expresses a planned action, just like English I’m going to pay the DAS tomorrow.

So it can suggest:

• intention
• plan
• expectation

It is not just a dry future tense; it often sounds practical and planned.

Yes. It is grammatically correct.

But in everyday Brazilian Portuguese, Eu vou pagar o DAS amanhã sounds more natural and conversational.

A rough comparison:

• vou pagar = common, spoken, natural
• pagarei = more formal, more written, sometimes more emphatic

Yes. Here are some natural alternatives:

• Amanhã eu vou pagar o DAS.
• Eu vou pagar amanhã o DAS.
• Vou pagar o DAS amanhã.

The most neutral everyday version is probably still:

• Eu vou pagar o DAS amanhã.

Some reordered versions may sound more emphatic or less natural depending on context.

Yes, absolutely. It sounds natural, especially in a business, self-employment, or tax-related context.

A Brazilian speaker might say this when talking about:

• a tax payment
• a monthly business obligation
• a payment slip they need to settle the next day

So both the grammar and the overall phrasing are realistic for Brazilian Portuguese.