Faute de déclaration de sinistre, l’expertise commence tard.

Here, faute de means for lack of, in the absence of, or more naturally in context, because there was no.

So:

• Faute de déclaration de sinistre = For lack of an insurance claim declaration
• In smoother English: Because the claim was not reported

It is a fairly formal French expression, often used in administrative, legal, or written language.

In faute de + noun, French usually does not use an article.

So you say:

• faute de temps = for lack of time
• faute d’argent = for lack of money
• faute de déclaration = for lack of a declaration / because there was no declaration

This is just how the expression works. Adding an article would usually sound unnatural here.

Déclaration de sinistre is a set insurance expression. It means the reporting of a loss/incident/claim to the insurance company.

In insurance French:

• déclaration = report, notification
• sinistre = loss, damage event, claim-triggering incident

So this is not just any declaration. It is a specific administrative step in an insurance context.

No. This is a classic false friend.

In everyday English, sinister means something like threatening, evil, or ominous.
But French sinistre often means something very different in insurance language: loss, damage event, accident, or insured incident.

Examples:

• un sinistre automobile = a car insurance claim / car loss event
• déclarer un sinistre = to report a claim / report an insured incident

So in this sentence, sinistre has nothing to do with something spooky or evil.

Because de sinistre is being used in a classifying way, not to refer to one specific already-identified incident.

Compare:

• une déclaration de sinistre = an insurance claim report / a claim declaration
  → the type of declaration
• la déclaration du sinistre = the declaration of the specific incident
  → a particular incident already known to both speaker and listener

In administrative French, déclaration de sinistre is the standard fixed phrase.

Not exactly. In this context, l’expertise does not mean expert knowledge/skill.

Here, expertise means something like:

• expert assessment
• inspection by an expert
• appraisal
• claims assessment

In insurance French, it often refers to the process where an expert evaluates the damage.

So:

• l’expertise commence tard = the expert assessment starts late

This is another false friend or near-false-friend to watch out for.

Because expertise is a feminine singular noun: l’expertise.

French uses le or la depending on gender, but before a vowel sound, both become l’:

• la table
• l’expertise

The apostrophe is just the normal contraction before a vowel.

Commence is the present tense of commencer.

The present tense here can be used to state a general fact or typical consequence:

• Faute de déclaration de sinistre, l’expertise commence tard.
• If the claim is not reported, the assessment starts late.

This kind of present is common in formal statements, procedures, rules, and general observations.

Both are possible, but tard is more common and more natural in many cases.

• commence tard = starts late
• commence tardivement = starts belatedly / starts late

Tardivement sounds a bit more formal or stylistically heavier.
In ordinary modern French, tard is usually preferred.

Here, tard is an adverb. It modifies commence:

• l’expertise commence tard = the assessment starts late

Compare:

• un départ tardif = a late departure
  → tardif is an adjective
• partir tard = to leave late
  → tard is an adverb

So in your sentence, tard describes how late the action begins.

Yes. A very natural alternative is:

• L’expertise commence tard faute de déclaration de sinistre.

This puts the main statement first and the cause after it.

Both versions are correct:

• Faute de déclaration de sinistre, l’expertise commence tard.
• L’expertise commence tard faute de déclaration de sinistre.

Putting faute de... first gives slightly more emphasis to the cause.

Yes, it sounds fairly formal, administrative, and insurance-related.

Clues:

• faute de is more formal than everyday alternatives like parce qu’il n’y a pas eu...
• déclaration de sinistre is technical insurance vocabulary
• expertise in this sense is also professional jargon

A more everyday paraphrase might be:

• Comme le sinistre n’a pas été déclaré, l’expert intervient tard.
• Comme la déclaration n’a pas été faite, l’expertise commence tard.

Yes. Faute de can be followed by:

• a noun: faute de temps
• an infinitive: faute d’avoir déclaré le sinistre

For example:

• Faute d’avoir déclaré le sinistre, l’expertise commence tard.

That means roughly:

• Because the claim was not declared/reported, the assessment starts late.

The noun version in your sentence is more compact and more administrative in style.

A native speaker would likely understand it as an insurance-process statement meaning something like:

• Because the claim was not reported, the expert assessment starts late.
• Without a claim declaration, the appraisal process begins late.

So the sentence is not mainly about abstract grammar; it sounds like a practical warning about delay in handling an insurance case.