Vou pagar o DAS, pois o prazo é amanhã.

Portuguese often leaves out the subject pronoun when the verb form already makes the subject clear.

• Vou pagar = I am going to pay
• The form vou already tells you it is eu.

You could say Eu vou pagar o DAS, but in normal Brazilian Portuguese, leaving out eu is very common unless you want emphasis, contrast, or extra clarity.

Vou pagar is the very common spoken way to talk about the future in Brazilian Portuguese.

• Vou pagar = I’m going to pay / I’ll pay
• Pagarei = I will pay

Both are grammatically correct, but they feel different:

• Vou pagar sounds natural and everyday.
• Pagarei sounds more formal, written, or sometimes a bit stiff in conversation.

So in Brazil, vou + infinitive is often the most natural choice in speech.

With bills, taxes, fees, and invoices, Portuguese usually uses pagar directly with the thing being paid.

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

Using pagar por usually changes the meaning or sounds less natural here. It can mean pay for in the sense of covering the cost of something, but with bills and taxes, direct pagar + object is the normal pattern.

So pagar o DAS is the expected phrasing.

DAS is an acronym used in Brazil for a tax payment document, especially in the Simples Nacional system. Even though it is an acronym, Portuguese often uses an article with acronyms, especially when they refer to a specific known item.

So:

• o DAS = the DAS payment slip/document

The article is masculine because the underlying noun is masculine, especially documento.

This is very common in Portuguese:

• o CPF
• o RG
• o CNPJ
• o DAS

Here, pois means because, since, or as.

So:

• Vou pagar o DAS, pois o prazo é amanhã.
• I’m going to pay the DAS, because/since the deadline is tomorrow.

Compared with porque:

• porque is the most common everyday word for because
• pois is also correct, but it often sounds a bit more formal or written

So these are very close in meaning here:

• ..., pois o prazo é amanhã.
• ..., porque o prazo é amanhã.

In this sentence, pois gives the sentence a slightly more formal tone.

When pois is used to introduce an explanation or justification, it is commonly preceded by a comma.

So the structure is:

• statement + , pois
  • explanation

Example:

• Vou sair, pois já está tarde.
• I’m leaving, because it’s already late.

This punctuation is very typical when pois means because/since.

Prazo means deadline, due date, or time limit, depending on context.

In this sentence, it means the payment deadline or due date.

So:

• o prazo é amanhã = the deadline is tomorrow / it’s due tomorrow

This word is very common in administrative, financial, and work-related contexts.

Examples:

• Qual é o prazo? = What is the deadline?
• O prazo terminou. = The deadline ended.

In Portuguese, this structure is completely natural. Amanhã can work as the complement of é in this kind of sentence.

So:

• O prazo é amanhã.
• literally: The deadline is tomorrow.

This means:

• the due date falls on tomorrow
• tomorrow is the deadline

Portuguese often uses time expressions this way:

• A prova é amanhã. = The test is tomorrow.
• A reunião é amanhã. = The meeting is tomorrow.

So although the structure may feel slightly different from English, it is normal Portuguese.

Yes, absolutely. In fact, that can sound even more specific in payment contexts.

Compare:

• o prazo é amanhã = the deadline is tomorrow
• o prazo vence amanhã = the deadline expires tomorrow / it is due tomorrow

You may also hear:

• O DAS vence amanhã.
• O vencimento é amanhã.

All of these are natural, but vence amanhã is especially common for bills, taxes, invoices, and payments.

It is mostly neutral, but pois makes it sound a little more formal or written than everyday casual speech.

A more casual version might be:

• Vou pagar o DAS porque o prazo é amanhã.

The original sentence is still perfectly natural, especially in messages, emails, or slightly more careful speech. It is not overly formal, just a bit more polished than the version with porque.