Na vijf dagen kwam de terugbetaling eindelijk binnen.

Because binnenkomen is a separable verb in Dutch.

• Full infinitive: binnenkomen
• In a main clause with a finite verb, the prefix often splits off:
  • kwam ... binnen

So in this sentence:

• kwam = the past tense finite verb
• binnen = the separated particle at the end

This is very common in Dutch:

• aankomen → Hij kwam laat aan.
• opbellen → Ik bel je morgen op.
• binnenkomen → De terugbetaling kwam binnen.

Here binnenkomen means something like to come in / to arrive / to be received.

This is because Dutch main clauses follow the verb-second rule.

The first element in the sentence is Na vijf dagen. Once that time phrase takes first position, the finite verb must come next:

• Na vijf dagen = first position
• kwam = second position
• de terugbetaling = subject after the verb

So:

• Na vijf dagen kwam de terugbetaling eindelijk binnen.

If the subject came first, you would get:

• De terugbetaling kwam na vijf dagen eindelijk binnen.

Both are grammatical. The original sentence puts more emphasis on the time phrase after five days.

Kwam is the simple past of komen.

Here are the key forms:

• infinitive: komen = to come
• present: komt = comes
• simple past: kwam = came
• past participle: gekomen = come

With the separable verb:

• infinitive: binnenkomen
• simple past: kwam ... binnen
• perfect: is binnengekomen

So this sentence uses the past form of binnenkomen:

• kwam ... binnen = came in / arrived / was received

Because na and nadat are used differently.

• na is a preposition, so it goes before a noun phrase:
  • na vijf dagen = after five days
• nadat is a conjunction, so it introduces a clause:
  • nadat hij vijf dagen had gewacht = after he had waited five days

So in this sentence, vijf dagen is just a time expression, not a full clause, so na is the correct word.

After a number, Dutch normally just uses the noun directly, without an article:

• vijf dagen = five days
• drie weken = three weeks
• tien minuten = ten minutes

You would only use an article if you meant a specific set of five days already known from context:

• de vijf dagen daarna = the five days after that

But here it simply means a duration, so na vijf dagen is the normal form.

Terugbetaling is a noun meaning refund, repayment, or reimbursement, depending on context.

It is built from:

• terug = back
• betaling = payment

So literally it is something like paying back.

In real usage, de terugbetaling often refers to:

• a refund from a company
• money paid back
• reimbursement of an amount

A related verb is:

• terugbetalen = to pay back / refund

So:

• De terugbetaling kwam binnen = the refund arrived / was received

Because terugbetaling is a de-word.

In Dutch, every noun takes either de or het, and this usually has to be learned noun by noun. For this word, the correct article is:

• de terugbetaling

Also, many nouns ending in -ing are de-words:

• de betaling
• de bestelling
• de vergadering
• de terugbetaling

So the article here follows a very common pattern.

Originally, yes, binnen is related to the idea of inside / inward / indoors. But in many expressions it has a more idiomatic meaning.

With things like messages, payments, documents, or applications, binnenkomen often means:

• to come in
• to arrive
• to be received

So in this sentence, binnen does not mean a physical inside location in a literal way. It means the refund finally came through or was received.

For example:

• Het geld is binnen. = The money has arrived.
• De e-mail kwam binnen. = The email came in.
• De terugbetaling kwam binnen. = The refund came in.

Eindelijk means finally, and its position is quite natural in the Dutch middle field of the sentence.

Here the order is:

• Na vijf dagen = time phrase in first position
• kwam = finite verb
• de terugbetaling = subject
• eindelijk = adverb
• binnen = separable particle at the end

So:

• Na vijf dagen kwam de terugbetaling eindelijk binnen.

This placement sounds very natural. It emphasizes that the refund took a while and then, at last, arrived.

A version like De terugbetaling kwam eindelijk binnen is also natural. Dutch adverb placement is somewhat flexible, but this sentence has a very standard word order.

Yes. Dutch often allows both the simple past and the perfect, depending on style, region, and context.

You could say:

• Na vijf dagen kwam de terugbetaling eindelijk binnen.
• Na vijf dagen is de terugbetaling eindelijk binnengekomen.

The difference is roughly:

• kwam binnen = simple narrative past; common in written storytelling and straightforward narration
• is binnengekomen = perfect; very common in everyday spoken Dutch

Both are correct. The original sentence simply uses the simple past.

Yes. Structurally, kwam ... binnen really does correspond to came in, but the best English translation depends on context.

Possible English equivalents are:

• the refund finally came in
• the refund finally arrived
• the refund was finally received
• the refund finally came through

So if you are learning the Dutch structure, it is useful to understand it literally as came in, but in natural English you might choose a different wording.

Yes, and that is often very natural.

Compare:

• De terugbetaling kwam eindelijk binnen.
  Focus on the refund process/payment as such

• Het geld kwam eindelijk binnen.
  Focus on the money itself

Both are fine, but they sound slightly different in emphasis. Dutch often uses either the abstract noun (de terugbetaling) or the concrete noun (het geld) depending on what the speaker wants to highlight.

Yes, but the difference is small.

• Na vijf dagen = after five days
• Vijf dagen later = five days later

Both can work in many contexts, but they frame the timing a little differently:

• Na vijf dagen emphasizes the amount of time that passed
• Vijf dagen later sounds a bit more like a narrative step forward in time

So this sentence could also be:

• Vijf dagen later kwam de terugbetaling eindelijk binnen.

That would still be natural, but the original wording is perfectly normal and slightly more neutral.