De retourzending kwam binnen de levertijd aan.

Because aankomen is a separable verb in Dutch.

• The full verb is aankomen = to arrive
• In a main clause with a finite verb, Dutch often splits separable verbs:
  • kwam = the conjugated part
  • aan = the separated particle

So:

• De retourzending kwam ... aan.

This is very common in Dutch:

• Ik kom morgen aan.
• De trein kwam op tijd aan.

In an infinitive or participle, the parts stay together:

• De retourzending zal morgen aankomen.
• De retourzending is aangekomen.

Both are possible, but they feel a bit different.

• kwam ... aan = simple past; often used in storytelling, reports, or written narration
• is aangekomen = present perfect; very common in everyday spoken Dutch when talking about a completed event

So these are both grammatical:

• De retourzending kwam binnen de levertijd aan.
• De retourzending is binnen de levertijd aangekomen.

The first can sound a little more narrative or formal, while the second is often more conversational.

Retourzending is a compound noun:

• retour = return
• zending = shipment / consignment / sent item

So retourzending means something like:

• return shipment
• returned package
• item sent back

Dutch makes compound nouns very freely, so this structure is normal.

Also, the article is de because the main part of the compound is zending, and de zending is a de-word.

Here binnen means within.

In this sentence, it introduces a time limit:

• binnen de levertijd = within the delivery time / before the delivery deadline expires

So it is not the same as inside in a physical sense. It is about time, not location.

Examples:

• binnen een uur = within an hour
• binnen drie dagen = within three days
• binnen de termijn = within the deadline/period

Levertijd is another compound noun:

• leveren = to deliver
• tijd = time

So levertijd means the delivery time, delivery period, or promised delivery window.

Depending on context, it can refer to:

• how long delivery is expected to take
• the allowed delivery period
• the promised timeframe for arrival

In this sentence, it means the return shipment arrived before that delivery period ran out.

Because in Dutch main clauses with a separable verb, the pattern is usually:

• subject
• finite verb
• middle information (time, manner, place, etc.)
• separated particle at the end

So:

• De retourzending kwam binnen de levertijd aan.

sounds natural.

Putting aan earlier is usually wrong in a normal main clause:

• De retourzending kwam aan binnen de levertijd. — this sounds unnatural or incorrect in standard Dutch

The particle aan normally stays at the end.

No. In this sentence, aan is not functioning independently as a preposition. It is part of the separable verb aankomen.

So you should understand:

• kwam ... aan = arrived

not as:

• came ... on/to

This is an important point for English speakers, because Dutch particles often look like ordinary prepositions, but in separable verbs they belong to the verb.

You have to learn whether a noun is a de-word or a het-word.

Here:

• de zending
• de tijd

Since Dutch compounds usually take the gender/article of the last part of the compound:

• retourzending ends in zending → de retourzending
• levertijd ends in tijd → de levertijd

This is a useful rule for compounds in Dutch.

Yes, absolutely. That is a very natural alternative.

Compare:

• De retourzending kwam binnen de levertijd aan.
• De retourzending is binnen de levertijd aangekomen.

Both mean essentially the same thing. The difference is mostly grammatical style:

• kwam ... aan = simple past
• is aangekomen = present perfect

In everyday speech, many Dutch speakers would often prefer the perfect tense.

They are similar, but not always identical.

• op tijd = on time, not late
• binnen de levertijd = within the delivery period / before the allowed delivery window ended

In many situations they lead to the same practical idea, but binnen de levertijd is more specific and tied to an official or expected timeframe.

For example:

• Het pakket kwam op tijd aan. = The package arrived on time.
• Het pakket kwam binnen de levertijd aan. = The package arrived within the promised delivery period.

The second one sounds more precise and logistical.

The structure is:

• De retourzending = subject
• kwam = finite verb (past tense of komen)
• binnen de levertijd = time-related phrase
• aan = separable particle completing aankomen

So the pattern is:

• Subject + finite verb + adverbial phrase + separable particle

This is a very common Dutch sentence pattern, especially with separable verbs.