Desalfandegamos o envio, contanto que pague os encargos aduaneiros.

Because contanto que normally requires the subjunctive.

So after contanto que, Portuguese uses a verb form that expresses a condition, not a simple statement of fact. That is why you get:

• contanto que pague = provided that you/he/she pay(s)

Here, pague is the present subjunctive of pagar.

Compare:

• Ele paga os encargos. = He pays the charges.
• Contanto que ele pague os encargos. = Provided that he pays the charges.

So the key point is: the conjunction triggers the subjunctive.

Contanto que is a fixed expression meaning:

• provided that
• as long as
• on condition that

It introduces a condition that must be met.

In this sentence, the idea is:

• We clear the shipment, provided that you pay the customs charges.

Also, que here is part of the whole expression contanto que. You should learn it as one unit, not word by word.

Portuguese often omits subject pronouns because the verb form and the context usually make the meaning clear.

Here, pague could refer to:

• você
• o senhor / a senhora
• or a third person, depending on context

In a customer-service sentence like this, it most likely means an omitted polite you.

So the implied sense is:

• ...contanto que você pague os encargos aduaneiros.

Portuguese very often leaves você unstated.

No. If you are using tu, the verb would change.

You would say:

• Desalfandegamos o envio, contanto que pagues os encargos aduaneiros.

That is because the present subjunctive of pagar changes by person:

• eu pague
• tu pagues
• ele/ela/você pague
• nós paguemos
• vocês/eles paguem

So pague fits você or ele/ela, while pagues fits tu.

In Portuguese, especially in business or service language, the present indicative can be used for something that is effectively a near-future action or a firm arrangement.

So:

• Desalfandegamos o envio

can naturally mean:

• We clear the shipment
• or, in English style, We’ll clear the shipment

English often prefers the future here, but Portuguese can sound perfectly natural with the present.

It is the 1st person plural present indicative of desalfandegar:

• nós desalfandegamos

That means we clear through customs or we handle the customs clearance.

The subject nós is omitted because Portuguese often leaves it out when the verb already shows the person clearly.

So:

• Desalfandegamos o envio
  literally = We clear the shipment through customs

Yes, but it is more common in logistics, customs, shipping, and administrative language than in casual everyday conversation.

A Portuguese speaker in this context would understand it immediately. It is a normal technical/business word.

In less technical speech, you might also hear things like:

• fazer o desalfandegamento
• tratar do desalfandegamento
• libertar na alfândega depending on context

So desalfandegar is correct and natural, but it sounds somewhat specialized.

Here, o envio means something like:

• the shipment
• the consignment
• the item sent

It is slightly more logistics-oriented and more neutral/technical than a encomenda.

Very roughly:

• envio = shipment / sending / dispatched item
• encomenda = parcel / order / package

In many real situations they overlap, but envio fits especially well in transport and customs language.

Encargos aduaneiros means customs charges.

This is a fairly broad term and can include things like:

• customs duties
• VAT/import tax
• administrative or processing fees linked to customs clearance

The adjective aduaneiro means related to customs.

So this phrase is a practical, official-sounding way to refer to the money that must be paid because the shipment is going through customs.

Because contanto que pague os encargos aduaneiros is a subordinate clause introducing the condition.

In standard written Portuguese, it is very natural to separate that kind of clause from the main clause with a comma:

• Desalfandegamos o envio, contanto que pague os encargos aduaneiros.

The comma helps show the structure clearly:

• main clause: Desalfandegamos o envio
• conditional clause: contanto que pague os encargos aduaneiros

So the comma is standard and stylistically appropriate here.