Se o valor não aparecer no extrato, eu vou ligar para o banco amanhã.

Because after se when Portuguese talks about a possible future condition, it usually uses the future subjunctive.

So:

• Se o valor não aparecer... = If the amount doesn’t appear / if the amount should not appear...

For many regular verbs, the future subjunctive looks exactly like the infinitive:

• aparecer → future subjunctive aparecer
• falar → falar
• comer → comer

That is why it may look like the infinitive, but here it is actually a verb form used in a conditional clause.

Compare:

• Se ele aparecer, me avise. = If he shows up, let me know.
• Quando o valor aparecer, eu aviso. = When the amount appears, I’ll let you know.

This is a very important pattern in Portuguese.

Here, se means if.

It introduces a condition:

• Se o valor não aparecer no extrato... = If the amount doesn’t appear on the statement...

Be careful: se can have other uses in Portuguese, but in this sentence it is simply the conjunction if.

Valor here means amount, sum, or charge.

In banking or financial contexts, valor often refers to a monetary figure, for example:

• o valor da compra = the amount of the purchase
• o valor cobrado = the amount charged

So in this sentence, o valor is probably a transaction amount, deposit, payment, or charge that the speaker expects to see on the bank statement.

It does not necessarily mean value in the abstract English sense, even though that is also a possible translation in other contexts.

In this context, extrato means a bank statement or account statement.

Examples:

• extrato bancário = bank statement
• ver o extrato = to check the statement
• o valor não apareceu no extrato = the amount didn’t show up on the statement

On its own, extrato can have other meanings in other contexts, but with banco and money-related language, learners should usually think of statement.

Vou ligar is the very common near future / periphrastic future in Brazilian Portuguese:

• vou ligar = I’m going to call / I will call

Although ligarei is grammatically correct, it sounds more formal or less common in everyday spoken Brazilian Portuguese.

So:

• Eu vou ligar para o banco amanhã. = natural, common spoken Brazilian Portuguese
• Ligarei para o banco amanhã. = correct, but more formal or written

In conversation, Brazilians very often prefer ir + infinitive for future actions.

Yes, eu could be omitted:

• Se o valor não aparecer no extrato, vou ligar para o banco amanhã.

That sounds natural too.

Portuguese often drops subject pronouns when the verb already makes the subject clear. Since vou clearly means I am going, eu is not required.

However, eu may still be used for:

• emphasis
• contrast
• clarity
• a slightly more explicit style

For example:

• Eu vou ligar, mas ele não vai. = I’m going to call, but he isn’t.

So in your sentence, eu is optional but perfectly natural.

Yes. Ligar has more than one common meaning.

Two very common ones are:

1. to call / phone

   • ligar para alguém = to call someone

2. to turn on / switch on

   • ligar a televisão = to turn on the TV

In this sentence, because of para o banco, it clearly means to call:

• ligar para o banco = to call the bank

This is very common in Brazilian Portuguese.

Yes, but in Brazilian Portuguese, ligar para is much more common and natural in everyday speech.

So:

• ligar para o banco = the usual Brazilian way
• ligar ao banco = grammatical, but less common in Brazil and may sound more formal or more European Portuguese-like

If you are learning Brazilian Portuguese, ligar para is the safer choice.

Because in Portuguese, não normally goes directly before the verb it negates.

So:

• não aparecer = not appear
• não vou ligar = I’m not going to call
• não está aqui = it isn’t here

In your sentence, the thing being negated is the action aparecer:

• Se o valor não aparecer... = If the amount does not appear...

That word order is the standard one.

Because the sentence begins with a conditional clause:

• Se o valor não aparecer no extrato, = If the amount doesn’t appear on the statement,
• eu vou ligar para o banco amanhã. = I’m going to call the bank tomorrow.

In both Portuguese and English, a comma is commonly used after an introductory if-clause when it comes first.

If you reverse the order, the comma is often omitted:

• Eu vou ligar para o banco amanhã se o valor não aparecer no extrato.

Both versions are correct.

Yes, amanhã can move around.

Your sentence has:

• eu vou ligar para o banco amanhã

This is very natural.

But Portuguese also allows:

• amanhã eu vou ligar para o banco
• eu vou amanhã ligar para o banco — possible, but less natural
• eu amanhã vou ligar para o banco — possible, often for emphasis

The most neutral and natural placements are usually:

• at the beginning: Amanhã, eu vou ligar para o banco.
• at the end: Eu vou ligar para o banco amanhã.

Putting amanhã at the end is very common and sounds completely normal.

Yes. O valor is singular because the sentence refers to one specific amount.

If there were several amounts, you would use the plural:

• Se os valores não aparecerem no extrato, eu vou ligar para o banco amanhã.

Notice that other words also change:

• o valor → os valores
• aparecer → aparecerem

So the singular here matches the idea of one particular charge, payment, or transaction amount.

Yes, but the tone changes a little.

• Se o valor não aparecer no extrato... = If the amount doesn’t appear...
• Caso o valor não apareça no extrato... = In case the amount doesn’t appear...

With caso, Portuguese usually uses the present subjunctive:

• caso ... não apareça

This version sounds a bit more formal or written.

For everyday conversation, se o valor não aparecer... is very natural and common in Brazilian Portuguese.