De polishouder vult het schadeformulier in.

Because invullen is a separable verb in Dutch.

• invullen = to fill in
• In a normal main clause, the conjugated part goes in the usual verb position, and the particle in moves to the end.

So:

• De polishouder vult het schadeformulier in.

Compare:

• infinitive: invullen
• main clause: hij vult ... in
• subordinate clause: ... dat hij het schadeformulier invult

This is very common in Dutch:

• opbellen → Ik bel je morgen op.
• aandoen → Hij doet het licht aan.

Vult is the present tense, third person singular form of vullen.

The subject is de polishouder = the policyholder, which is singular, so Dutch uses:

• ik vul
• jij/u vult
• hij/zij vult

With the separable verb, the full verb is invullen, but only the main verb part is conjugated here:

• invullen → vult ... in

Polishouder means policyholder, especially in an insurance context.

It is a compound noun:

• polis = insurance policy
• houder = holder

So polishouder literally means policy holder.

A native English speaker might momentarily think of polish as in making something shiny, but that is unrelated. Dutch polis means policy here.

Dutch nouns have grammatical gender, and that affects whether they take de or het.

• de polishouder
• het schadeformulier

A useful rule for compounds is this:

The article is determined by the last part of the compound.

So:

• houder is a de-word → de polishouder
• formulier is a het-word → het schadeformulier

This is a very helpful pattern in Dutch compound nouns.

Schadeformulier is a compound noun:

• schade = damage, loss, claim-related damage
• formulier = form

So literally it is a damage form, but in natural English, depending on context, it is usually something like:

• claim form
• damage claim form
• accident report form

In insurance language, the exact English translation often depends on the situation.

No, not in this sentence.

Here, in is the particle belonging to the separable verb invullen. It is not functioning like a separate preposition with its own object.

So:

• vullen = to fill
• invullen = to fill in

That means in is part of the verb’s meaning.

Normally, no.

In a standard main clause with a separable verb, the particle usually comes after the object:

• De polishouder vult het schadeformulier in. ✅

Not:

• De polishouder vult in het schadeformulier. ❌

With pronouns, Dutch can look a bit different:

• Hij vult het in.

But in your sentence, the normal order is definitely:

• vult + object + in

Because Dutch writes compound nouns as one word much more often than English does.

So Dutch prefers:

• schadeformulier
• polishouder

not:

• schade formulier
• polis houder

This is one of the most noticeable differences from English. If two nouns belong together as one concept, Dutch usually joins them into a single word.

The separable verb behaves differently depending on sentence type.

Question:

• Vult de polishouder het schadeformulier in? = Does the policyholder fill in the claim form?

Subordinate clause:

• Ik weet dat de polishouder het schadeformulier invult. = I know that the policyholder fills in the claim form.

Notice the difference:

• main clause: vult ... in
• subordinate clause: invult

That is a key pattern with separable verbs.

No.

In Dutch, de does not automatically mean masculine in everyday usage. It mainly tells you that the noun is a common-gender noun rather than a het-word.

So de polishouder can refer to a person of any gender. It simply means the policyholder.

A rough English-friendly approximation is:

duh po-LEES-how-der vult hut SKHAA-duh-for-mu-leer in

A few notes:

• polis sounds roughly like po-lees
• sch in schade is a hard Dutch sound, not like English sh
• vult has a short u sound, not like English full, but somewhat similar
• formulier has stress near the end: for-mu-LIER

This is only an approximation, but it can help you get started.