bansong baesongbireul meonjeo naessseupnida.

반송 배송비 is a noun phrase made of:

• 반송 = return shipment / sending something back
• 배송비 = shipping fee / delivery charge

In Korean, it is very common to place one noun before another to modify it. So 반송 배송비 means the shipping fee for returning something or return shipping cost.

This is similar to English noun-noun combinations like:

• school bus
• coffee cup
• return shipping fee

Korean often builds these meanings without extra words like for or of.

Because 배송비 is the main noun being acted on.

• 반송 modifies 배송비
• 배송비를 marks shipping fee as the object of the verb 냈습니다

So the structure is:

• 반송 배송비를 = the return shipping fee
  • object marker

You can think of 반송 배송비 as one unit, and 를 attaches to the whole noun phrase by attaching to the final noun.

먼저 means first, beforehand, or in advance, depending on context.

In this sentence, it tells you that the paying happened earlier than some other action. For example:

• paid the return shipping fee first
• paid the return shipping fee in advance

Its placement is flexible in Korean. Here it comes before the verb:

• 반송 배송비를 먼저 냈습니다.

That is a very natural position. You may also see adverbs like this in other places depending on emphasis.

The dictionary form is 내다, which has several meanings, including to pay in expressions involving money.

When conjugated in the polite formal past tense:

• 내다 → 냈습니다

This happens because:

• 내다 → stem 내-
• past marker -었- combines with it
• 내었 contracts to 냈

So:

• 내었습니다 → 냈습니다

This contraction is normal and very common.

In money-related contexts, yes, 내다 often means to pay.

But it is a broader verb than English pay. Depending on context, 내다 can also mean things like:

• to submit
• to produce
• to send out
• to emit
• to hand in

For money, though, expressions like these are very common:

• 돈을 내다 = to pay money
• 비용을 내다 = to pay a cost
• 요금을 내다 = to pay a fee
• 배송비를 내다 = to pay shipping

So in this sentence, 냈습니다 naturally means paid.

Because Korean often omits the subject when it is clear from context.

So 반송 배송비를 먼저 냈습니다 could mean:

• I paid the return shipping fee first.
• We paid the return shipping fee first.
• He/She paid the return shipping fee first.

The actual subject depends on the situation. In Korean, leaving it out is very normal if the listener already knows who is being talked about.

냈습니다 is in the formal polite style, often called -습니다 style.

It is commonly used in:

• customer service
• business communication
• announcements
• written explanations
• polite reporting of facts

It sounds more formal than:

• 냈어요 = polite but less formal
• 냈어 = casual

So this sentence has a fairly formal and neutral tone.

Yes. That would be grammatically correct and natural in less formal speech.

Compare:

• 반송 배송비를 먼저 냈습니다. = formal polite
• 반송 배송비를 먼저 냈어요. = standard polite, less formal
• 반송 배송비를 먼저 냈어. = casual

The meaning stays the same; only the speech level changes.

Not exactly, though they are related.

• 반품 usually means returning an item, especially in shopping contexts
• 반송 focuses more on sending something back or return shipment

So:

• 반품 배송비 often appears when talking about return fees in online shopping
• 반송 배송비 emphasizes the shipping cost involved in sending the item back

In real usage, the preferred word can depend on the company, platform, or context.

It is pronounced roughly like 냈씀니다 in actual speech.

A helpful breakdown:

• 냈습니다 is written with ㅅㅂ
• in pronunciation, this often sounds closer to ㅆㅁ

So learners often hear something like:

• nae-sseum-ni-da

You do not need to change the spelling; this is just a pronunciation effect that happens naturally in Korean.

Yes. That is usually the implication.

먼저 suggests an order of actions, such as:

• first paying the return shipping fee
• then doing something else afterward

Exactly what comes later depends on context. For example:

• first paid the fee, then sent the item
• first paid the fee, then requested the return
• first paid the fee, then waited for processing

So 먼저 often signals this happened before another relevant step.

By itself, it is grammatically complete and natural, but it does rely on context for full interpretation.

For example, a listener may still wonder:

• Who paid it?
• Why was it paid first?
• Before what action?
• Which return shipping fee?

That is very normal in Korean. Sentences are often shorter and more context-dependent than in English. So even though it may feel slightly incomplete to an English speaker, it is perfectly natural Korean.