Le client conteste le trop-perçu.

Because trop-perçu is being used as a noun here, not just as a descriptive expression. In French, nouns normally need an article, so you say le trop-perçu.

Here, le trop-perçu means something like the overpayment, the excess amount received, or the amount charged/paid in excess, depending on context.

So the structure is:

• Le client = the customer/client
• conteste = disputes/challenges
• le trop-perçu = the overpayment / excess amount

It is a compound noun.

It comes from:

• trop = too much
• perçu = received, collected

Together, un trop-perçu refers to money received or collected in excess.

So even though perçu originally looks like a past participle, the whole expression functions as a regular noun here.

Because it is a fixed compound word. In French, many compound nouns are written with a hyphen, especially when they are formed from two elements that work together as one unit.

So trop-perçu is treated as one lexical item, not as two separate words in this sentence.

Because this is the standard French sentence pattern:

subject + verb + direct object

So:

• Le client = subject
• conteste = verb
• le trop-perçu = direct object

French word order is often similar to English in straightforward statements, so this part is quite normal.

It is related, but in everyday English, contest is less common as a verb in this exact sense. In French, contester very commonly means:

• to dispute
• to challenge
• to question the validity of

So in many contexts, disputes is the most natural English translation.

This is a useful word to learn because it is common in administrative, legal, and customer-service language.

It is the present tense, third person singular, of contester.

So:

• je conteste = I dispute
• tu contestes = you dispute
• il / elle / on conteste = he/she/one disputes

Since le client is singular, the verb is conteste.

Le client is the masculine singular form.

If the customer is specifically female, you would usually say:

• La cliente conteste le trop-perçu.

So French often marks gender in nouns referring to people.

Usually customer is the more natural choice in many everyday contexts, especially billing, shops, services, and complaints.

But client can also be translated as client in English in some professional contexts, such as law, consulting, or business services.

So the best English word depends on the situation, even though the French word is the same.

Because trop-perçu is a masculine noun: le trop-perçu.

Even though perçu looks like a past participle, in this fixed noun it stays in the standard masculine singular form.

So you learn it as a set expression:

• un trop-perçu
• des trop-perçus

A rough pronunciation is:

troh pair-SYOO

More approximately in IPA:

/tʁo pɛʁ.sy/

A few points:

• trop sounds like troh
• perçu has the French u sound at the end, which does not exist exactly in English
• the final -çu is pronounced syu with a French u, not like English soo

It sounds fairly administrative, billing-related, or formal-neutral.

Both contester and trop-perçu are common in official or semi-official contexts such as:

• invoices
• reimbursements
• public administration
• banking
• customer complaints

It is perfectly normal French, but not especially casual conversation language.

Yes, depending on context.

Possible alternatives might include things like:

• surpaiement = overpayment
• somme perçue en trop = amount received in excess
• montant trop perçu = excess amount collected

But trop-perçu is a standard and very common term, especially in administrative French.

Strictly speaking, trop-perçu focuses on the idea of an amount received in excess. So from a technical wording point of view, it often refers to money that was collected or received when it should not have been.

In real context, that often corresponds to the customer having been overcharged or having paid too much. So the exact English translation may depend on who is being described in the wider situation.