En plus, l’assuré déclare le sinistre.

En plus usually means in addition, what’s more, or moreover in a sentence like this.

So here it works as a linking phrase that adds another step or another piece of information.

A few useful points:

• En plus = in addition / moreover
• En plus de + noun = in addition to + noun

Examples:

• En plus, il téléphone au client. = In addition, he calls the client.
• En plus du rapport, il envoie une photo. = In addition to the report, he sends a photo.

So in your sentence, En plus is not really the adjective more by itself; it is acting like a discourse marker: also / additionally.

Because French avoids having two vowel sounds clash together.

Le becomes l’ before a word that starts with a vowel sound or a silent h:

• le client
• l’assuré
• l’homme

This is called elision.

So:

• le + assuré → l’assuré

It still means the insured person / the policyholder, but the form changes for pronunciation.

Here, l’assuré is a noun, not just a past participle or adjective.

In insurance language, un assuré means:

• the insured person
• the policyholder
• sometimes more generally the person covered by the insurance

That can be confusing because assuré can also be the past participle of assurer (to insure / to assure), as in:

• Le véhicule est assuré. = The vehicle is insured.

But in your sentence, l’assuré clearly functions as a person: the one who performs the action déclare.

Déclare is the present tense form of the verb déclarer for il / elle / on or for a singular noun like l’assuré.

Conjugation of déclarer in the present:

• je déclare
• tu déclares
• il/elle/on déclare
• nous déclarons
• vous déclarez
• ils/elles déclarent

Since l’assuré is singular, the verb takes the same form as il/elle:

• L’assuré déclare...

In many instructional or formal texts, the present tense is used to describe a general procedure:

• The insured reports the claim
• The company reviews the file
• The expert examines the damage

So this is the normal tense here.

Because déclarer can take a direct object.

In this sentence, le sinistre is the thing being declared, so it comes directly after the verb:

• déclarer quelque chose
• déclarer le sinistre
• déclarer un accident

That is why there is no preposition.

Be careful, though: French can also use déclarer quelque chose à quelqu’un when you mention the person or organization receiving the declaration.

For example:

• L’assuré déclare le sinistre à son assureur. = The insured reports the claim to his insurer.

So:

• thing reported = direct object
• person/company informed = often introduced with à

No, not in this context.

In insurance French, un sinistre means something like:

• a claim
• a loss
• an incident
• damage event
• insured event

Depending on context, it can refer to the event itself (accident, fire, water damage, etc.) or to the insurance claim arising from it.

It is related historically to the English word sinister, but the meanings are very different in modern usage.

For a learner, the important thing is:

• in insurance language, sinistre is a standard technical word
• it does not mean evil here

French often uses the definite article when referring to something already known from context, especially in procedural, legal, or administrative language.

So le sinistre may mean:

• the claim
• the incident in question
• the loss being discussed

In a process description, French often assumes the item is identifiable from the situation.

Compare:

• L’assuré déclare un sinistre. = The insured reports a claim / an incident.
  This introduces it more generally.
• L’assuré déclare le sinistre. = The insured reports the claim / the incident.
  This sounds more like the specific incident already being referred to.

Both are possible depending on context.

Yes, the word order is normal.

En plus at the beginning of the sentence works as a sentence adverb or linking expression. It comments on the whole statement:

• En plus, l’assuré déclare le sinistre.

This is very natural when listing steps or adding information.

If you say:

• L’assuré déclare en plus le sinistre,

it sounds more like the insured also reports the claim, with stronger focus on that extra action. It is not impossible, but it is less neutral and less likely in a straightforward procedural sentence.

So sentence-initial En plus is a common and natural choice.

A helpful approximate pronunciation is:

ahn plu, lah-syur-ay day-klahr luh see-neestr

A few details:

• l’assuré: the l’ links directly to assuré
• assuré has the stress pattern typical of French, with the final syllable sounding like -ré
• déclare sounds roughly like day-klahr
• sinistre is pronounced with two clear syllables after si-: roughly see-neestr

Important pronunciation notes:

• The accent in déclare helps show the sound é = roughly ay
• The apostrophe in l’assuré shows that le lost its final vowel before assuré

Yes, very much so.

In insurance contexts, déclarer un sinistre is a standard expression meaning:

• to report a claim
• to notify the insurer of a loss/incident
• to file a claim (depending on context)

Other common insurance expressions include:

• faire une déclaration de sinistre = to make a claim report
• déclarer un accident = to report an accident
• ouvrir un dossier = to open a file/case
• être indemnisé = to be compensated

So this sentence uses typical formal insurance vocabulary.

Yes, but it would change the meaning completely.

• l’assuré = the insured person / policyholder
• l’assureur = the insurer / insurance company

They are easy to confuse because they look similar.

Compare:

• L’assuré déclare le sinistre.
  = The insured person reports the claim.
• L’assureur traite le sinistre.
  = The insurer handles the claim.

So the ending matters a lot:

• -é → insured person
• -eur → insurer/company/person who insures